The 50/50 Conundrum

One of the complaints I hear most often about baseball board games like Strat-O-Matic is that they utilize a 50/50 model. This is a game mechanic where the result of the at bat is randomly read from the batter’s card half the time and the pitcher’s card the other half. Thus, the classic batter vs. pitcher duel isn’t a duel at all; it’s only ever influenced by one player or the other (and, of course, the occasional fielder).

Growing up, this bothered me, too. In fact, it bothered me most whenever I played Statis Pro Baseball and the pitcher on the mound had a large PB range (e.g., 2-9). I would look longingly at all the doubles and homeruns available on the batter’s card and know the moment I read the next fast action card and realized the result would come from the pitcher’s card they were all for naught.

I noticed it less in Strat-O-Matic because it utilized the 50/50 model and at least that seemed fair. Nevertheless, in critical situations my favorite pitcher or batter was reduced to being a mere spectator.

These days I don’t play board games very often but out of a sense of nostalgia in part driven by the work I’ve put into my own game, Trivia Challenge Baseball, I’ve been watching a lot of YouTube videos produced by folks who do and a few of them complain about it, too— or at least tout those games that include batter-pitcher interactions for each at bat as vaguely superior in this regard.

It got me thinking: does it really matter? The first thing I thought was that if you take a Strat-O-Matic batter and pitcher card and tape them together, you essentially have a single card where the pitcher and batter both influence the results of the at bat. Certainly no one would argue it wouldn’t produce the same results the two cards produced separately before they were taped together.

Of course, some might argue the 50/50 model is still in place in this example, since that batter columns are still 1 thru 3 and the pitcher columns 4 thru 6.

If we wanted to, we could cut out every dice roll result from the pitcher and batter cards and randomly assign them to a column (1 thru 6) on a new card. Indeed, we could physically create this sort of card with a pair of scissors, glue and the grotesque indifference required to defile Strat-O-Matic cards! Such a Frankenstein-like card, when constructed, would also produce the same results. None of the probabilities would have changed.

This would seem to suggest that the influence the pitcher has on the batter and vice-versa is still present in a 50/50 model and that our belief it isn’t is simply a misconception on our part.

If you aren’t buying any of this, that’s OK. Being skeptical is a good thing. So let’s explore things further. We’ll start with a definition: When are two sets of results the same?

I would posit they are the same if they both produce the “same” distribution and measures of central tendency, including streaks. To see what I mean, let’s consider a simple example: a batter’s hits. A hit, of course, is anything from a single to a homerun. I’ll assign a 1 to every hit and a 0 to every out. We’ll consider the following two sets representing 10 at bats:

Set 1 = {1, 0, 0, 1, 0, 0, 0, 1, 0, 1}

Set 2 = {1, 1, 1, 0, 0, 0, 0, 0, 1, 0}

Obviously a set of 10 outcomes is on the small side but don’t worry, I’m not making a scientific point here. Right now, I’m just trying to settle on a definition of “same.”

Note that both sets have the same mean and variance. They have the same mode and median. But they don’t quite look the same. Set 2 appears more “streaky”. When I think of the 50/50 model, I am convinced the mean is the same as the mean obtained from samples involving the combined contributions of the batter and pitcher, but I wonder about streaks.

To explore this further, imagine a .400 hitter facing a pitcher who allowed batters to hit just .150. (Though slightly more extreme, this is a little like pitting Ted Williams from 1941 against Pedro Martinez from 2000 when Ted batted .406 and Pedro allowed opposing hitters to bat just .167). Let’s assume the league average is .250. Thus, for our .400 hitter to bat his average in a 50/50 model, his card would need to represent a .550 average (since .550 × ½ + .250 × ½ = .400). Likewise, our superstar pitcher would allow just a .050 average on his card (.050 × ½ + .250 × ½ = .150). When facing each other, we expect our mythical batter to hit .300, since  .550 × ½ + .050 × ½ = .300.

I chose to use these fictional players for this example precisely because their cards are so different. I think intuitively we might be tempted to believe our .400 batter will be less streaky in a 50/50 model where his probability of getting a hit goes from .550 to .050 depending on whose card is read.

To test this theory, I’ll run a simulation where our .400 batter faces off against our superstar pitcher over a series of 100 million at bats. We will record the number of hits our batter accumulates over those at bats and calculate a few statistics. Note the combined results referred to below are those compiled by a .300 hitter while the split results are those obtained by randomly reading each result from the batter or pitcher card (i.e., our .400 batter and .050 pitcher).

Combined Results Statistic Split Results
.3001 Mean .3001
6,303,213 2 Hit Streaks 6,303,685
1,894,404 3 Hit Streaks 1,892,426
568,379 4 Hit Streaks 566,823
170,349 5 Hit Streaks 169,673
51,232 6 Hit Streaks 51,198
15,470 7 Hit Streaks 15,332
4,610 8 Hit Streaks 4,611
1,373 9 Hit Streaks 1,355
457 10 Hit Streaks 405

* Note: Steaks are defined as consisting of exactly the number of hits shown. For example, every 3 hit streak includes a 2 hit streak but these were not counted as 2 hit streaks. Put another way, all streaks are bracketed by outs.

Not surprisingly, the means are the same rounded to 4 decimals and very close to the .300 average we expected (which isn’t a surprise given the size of the sample). Even more encouraging are the streaks, which are very similar between the two sets.

If you’re the meticulous type and looked closely at the numbers in the table, you may have noticed the combined results seem to include more streaks, even though the sums are close. There are a couple of items worth noting. First, this was not true of other data sets I ran. Second, remember we are viewing the raw totals—not the percentages— and they tend to accentuate differences between the two sets.

The Law of Large Numbers governing probabilities does not imply differences will vanish as the sample size increases, only that the average (or mean) will tend to get closer to the expected value as the sample size increases. The next two graphs provide evidence of this fact. The first graph shows that the difference between the expected number of hits and the number of hits observed appears to be growing while the second graph shows how the difference between the calculated batting average and the expected batting average (.300) seems to be shrinking.

So where does this leave us? Well, for one thing, it seems to indicate that on an at bat-by-at bat basis the results from a 50/50 model are indistinguishable from those produced by models that simultaneously account for the pitcher and batter. This is a powerful statement and should be enough to end the argument.

And yet…

Perhaps, like me, you’re having a hard time getting over the fact that individual at bats are controlled by a single player. If so, I urge you to read the above paragraph again and let it sink in. We aren’t talking above averages or long term trends. If you take any set of results from a 50/50 model— including sets with just one, two or three at bats— you won’t be able to tell which model produced it.

The truth is, the batter-pitcher interactions do exist for every at bat in the 50/50 model and I can prove it. It’s the little white die you roll in Strat-O-Matic, for example, to determine which card to read. It may not look or feel like the sort of interaction you get with, say, Payoff Pitch Baseball or Replay Baseball, for example, but it’s there and produces the same outcomes.

I’ve identified the interactive mechanism but I said I’d prove it and I haven’t yet. I’ll do so by running another simulation featuring our two ballplayers, only this time I won’t roll a little white die to determine whose card to read, I’ll simply alternate between the two cards. In other words, I will use a “deterministic” 50/50 model.

Looking at the results, it is clear at a glance that the deterministic model does not produce the same results. Notice the means are the same but nothing else. It produces the kind of results critics of a 50/50 model would be correct to criticize. But, as we’ve seen, these aren’t the results 50/50 models produce.

Combined Results Statistic Split Results
.3000 Mean .3000
6,298,221 2 Hit Streaks 1,924,607
1,889,300 3 Hit Streaks 748,722
567,063 4 Hit Streaks 52,790
169,950 5 Hit Streaks 20,544
51,095 6 Hit Streaks 1,436
15,234 7 Hit Streaks 578
4,493 8 Hit Streaks 31
1,358 9 Hit Streaks 12
419 10 Hit Streaks 0

Still not convinced? How about we roll for it!


8 thoughts on “The 50/50 Conundrum

  1. Wow this is great stuff! I loved your J.R. Richard article and replay too! Your way too advanced for me to comprehend but I like what you say about the 50-50 model! I love Strat and have since 1976, but I also play 9-10 other baseball board games and some I like better than Strat, a couple not as much. I’m a big realism fan of course the fun factor means a ton as well so variety in games is what I like about all the ones I own.

    Can’t wait to try your trivia game, what a tremendously interesting concept and neat twist on tabletop baseball!

    Good luck and I am looking forward to when it becomes available for purchase!



    1. Hi John. Thanks! They do a great job with their YouTube videos and FB page. A great group of folks contribute there, too. As for the game: I’ve been dragging my feet a little with a Kickstarter because I’ve always suspected the audience for this sort of game is quite small. The tentative plan is to get a Kickstarter campaign going by next weekend so I can offer the 2018 Playoff teams. If that doesn’t happen I’m happy to make arrangements to sell you a game privately. I’m also hoping to post as many free things as I can here. I have about 90 teams worth of card images; I just have to put them onto a single sheet or two so people can copy them (right now they are individual images).


      1. Eric, this game is fantastic! My son and I played 15 games today (1st game was an exhibition game) he was the 16′ Cubs and I was 78′ Houston. Well I guess I’m not so good at baseball trivia after all, as he beat me 12-0! Then we decided to play two best of 7 game series.
        We picked teams blindly for the 1st series and he got the 1912 Red Sox and I drew the 98′ Yankees. Well I regained bragging rights as I swept him 4-0.
        Game #1 Andy Pettitte threw 6 innings of scoreless ball before he tired and I won 6-1.
        Game #2 David Wells won behind a strong offensive attack, 9-3
        Game #3 The Yanks got a shutout 6-0 as David Cone pitched a gem through 5 innings and the bullpen breezed through the Sox order the rest of the way.
        Game #4 Yet another Yankee shutout, this time by the score of 7-0 as Hideki Irabu baffled Red Sox batsmen throughout.

        The next series was a classic and went the full seven games! This time we picked what team we wanted to be and my son Nick chose the 61 Bronx Bombers and I took my beloved 69′ Orioles. Before this series we decided that teams can score an unlimited amount of runs in the 9th inning and bot did it come into play! As long as you are able to score any amount of runs per/roll and get the question correct, you roll again for the next hitter until the out is made. Mickey Mantle was an absolute terror in this series and Bobby Richardson (batting 9th) played the role of hero on more than 1 occasion.

        Game #1 Yankees blow O’s out 6-0 with Mantle scoring 4 in the 1st.

        Game #2 Frank Robinson puts 4 on the board for Baltimore in the 1st and then Brooks Robinson does the same in the 6th for an 8-0 lead! The Yanks get single runs in the 7th & 8th and then in the 9th trailing 8-2 New York takes advantage of the “unlimited rule” and rally for 7 runs taking a 9-8 lead. Luis Arroyo comes in the bottom 1/2 and shuts the door getting the save and giving The Yanks a 2-0 lead on a miracle comeback!

        Game#3 The Birds get 3 in the 1st from F. Robinson and the in the bottom of the 8th, Clete Boyer puts a 4 spot on the board giving the Yanks a 4-3 lead. In the top of the 9th, Boog Powell puts 2 on the board and the O’s now lead 5-4. In the bottom of the 9th The Yanks have a chance for 3 runs but Nick answered the trivia question incorrectly and the O’s hang on!

        Game#4 O’s get 1 in the 1st from F. Robinson, but Mantle strikes again for 4. Yogi Berra got another 4 in the 3rd and it was 8-1 N.Y. In the 3rd Mark Belanger was responsible for 3 Orioles runs and the B. Robinson put up 2 in the 6th, pulling Baltimore to within 2 @ 8-6.
        In the top of the 9th, Boog Powell in clutch fashion blasted in 4 runs to give the O’s a 10-8 lead. Nick once again had a chance to keep the inning going as Roger Maris had a chance for a 2 runner but he was stumped as he was in the last game and the series is now 2-2!

        Game#5 Whitey Ford pitched a CG allowing only 1 run and the Yanks win easy 5-1 and take a 3-2 lead in the series.

        Game#6 In an absolute masterpiece by southpaw Dave McNally (6 innings) the Birds hang on to shutout N.Y. 1-0! Ellie Hendricks got the run in the 7th and the Oriole bullpen held on!

        Game#7 Mantle does what he has all series and goes for 4 in the 1st. The Birds get on back in the bottom thanks to F. Robinson. Elston Howard put 4 more in the board for N.Y. in the second and then Don Buford answered back with 3 for Baltimore and it’s 8-4 Yankees after 2. Yanks make it 9-4 in the 3rd and then Baltimore scored 3 runs curtesy of Davey Johnson in the bottom of the 8th making it 9-7. After N.Y. fails to score in the 9th, mighty Boog Powell steps up and gets a hold of one for a possible 4 runs and the win. I choose to pass the trivia question tor Nick and if he gets it wrong I (The O’s) win the series. He gets the answer correct and staves off defeat as he throws his arms up in joy! Yankees win!! They take the amazing series 4-3 in dramatic fashion!

        Eric this game is tremendous and an absolute blast to play! Nick is 26 and he totally love it as well, we had so much fun and great bonding too! I love the way this plays. The really good/tough pitchers can totally dominate (not allowing a question to be asked) and the great hitters can really light up the scoreboard! You can clearly see the difference between the good to great hitters and pitchers compared to the bad to terrible ones! Plus the defense’s ability to stop runs shine through from time to time as well!

        This is genius and a totally different twist to tabletop baseball. Very clever and well thought out, with a perfect balance of difficult to not so difficult questions!

        Boy we sure had fun and we both really thought about how fun this game would/will be with two or more teams of 2! I thought we went through a ton of questions but my son said we didn’t even probably go through 1/4 of them. It may seem like or look like we missed a lot of questions, but the cool thing is that’s not the case at all. It just so happens that good pitcher don’t allow questions and average to below hitters don’t have the opportunities to put runs up due to not having good results in the right spots.

        Love this game and highly recommend it!

        Stay tuned for more

        Chris Hawes

        Liked by 1 person

  2. I’m not sure I comprehended the whole article but found it extremely interesting. So do you believe that a 50/50 game is a bust or not when it comes to reality. Have you ever played Dynasty League Baseball? Thoughts

    Liked by 1 person

    1. Hi Mick. My point is that the 50/50 system is indistinguishable from a system that combines pitcher and batter results together and is therefore every bit as realistic. I have not played Dynasty League. I am not immediately aware of any baseball games that are unrealistic, though I’d argue that those that utilize grades are likely to be less realistic since those sorts of adjustments tend to lump a wide range of differences into just a handful of “grades.” The least realistic board game I’ve played is APBA saddle racing, even though it is a favorite of mine.


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