Franchise Ball News
FB Math of the Game - Article 1 - Why Defense Does Not Really Matter
Dec 28th 2020 By Tacoma Storm

I was looking at my team management page, trying to see if my new FA acquisitions were any good. The player was pretty good, I gotta say. 90 POW, 90 CON, 70 SPD. But then I looked at his 60 DEF and thought, "This guy is not a worthy starter because his defense is shit". But then I used my very mathematical mind and figured out why it doesn’t matter.

Before we go on, I would like to tell everyone that this is a new series, with new articles coming out every 2 weeks. I hope that everyone is having an amazing offseason because I know I am.

Before we examine this further, you need to know some terminology. I suggest you go here to learn it because after all, this guy explains it very well. I encourage you to watch it because then, this article will make a lot more sense. It is a hypothetical scenario and is actually more interesting than you think.

https://www.youtube.com/watch?v=1csFTDXXULY&;list=PLNDkJw-bKYYG3ERrB2j4jEveS9a__F3M3&index=39

I hope you watched it, but if not, oh well. Anyway, on to the reasoning.

I messaged the Admins and asked if the defensive rating was proportional to the catching percentage (as in 60 DEF means a 60% catching rate). He said it was not but it is quite close to that, so that is what I will be basing it off of. Let’s say that Arnoldo Almanza (my LF) had a fly ball come in his direction. With his rounded 60 DEF rating, he has a 60% chance to catch a fly ball. That does not seem like great odds. So why should he be a starter on my team?

That is because we are so focused on the percentage that completely forgetting the probability that the ball comes to the LF in the first place. This is known as a base rate fallacy. In FB, there are 15 ways to get an out. A flyout and lineout each to center, left center, left, right center, and right, and a groundout to SS, 1B, 2B, and 3B, and a strikeout. The chances of the LF getting the ball is approximately 13%. Even though the chance of him catching the ball is not great, it is still higher than the chance of him getting the ball in the first place. Therefore, instead of a 40% error rate, it is actually approximately 5%, because 0.13 x 0.4 is approximately 0.05. This is known as an example of conditional probability.

So what is the lowest defensive rating you should aim for? I would say 50 DEF. Even though it does not seem great, my example of conditional probability and base rate fallacy proves otherwise. Obviously, you should aim for 90 DEF. However, if you see a 95/98/94/68 3B in free agency, you should still pick him up.

I used to be disgusted with my DEF ratings of guys that I was getting. But after I thought about this, I stopped worrying about it. Now, you can see lower defensive ratings on my team. But a common misconception that people have is that you should not have everyone with low defensive ratings, because then the error rate will go up.

I hope you enjoyed this article about FB Math of the Game. Have an amazing offseason!

Tacoma Storm

News Conversation
Storm : 
defense matters guys, when pettigrew makes errors in big games, defense matters kids
2 months ago
Storm : 
True lol
7 months ago
Cobras : 
lol no one cares its not going to stay that way
7 months ago
Storm : 
Fun fact - the guy I am using for this article (Almanza) has an AVG over .400 (top 10 in Alpha Ruby)
7 months ago
Maybe I misunderstood, but that's what I take away from what you wrote.
7 months ago
Also, I haven't seen a player on my team get more than 3 errors in a season, and my team isn't that great defensively in terms of ratings, but 3 errors for a 60 rated fielder seems like less than 40% of balls hit to him are errors.
7 months ago
If I understood this correctly, you're saying about 5% of balls hit that are possible outs would result in an error by the LF with 60 DEF, which is insanely high. If that's true, I'd be more worried about defense than ever.
7 months ago
Storm : 
Lol
7 months ago
Well, good lord, this is something. Dont worry, theres a formula for this. Its called Nats=Bitch
7 months ago
Storm : 
True
7 months ago
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