Comments on: Jered Weaver and Splits

By: Alireza

Alireza — Wed, 10 Feb 2010 04:58:15 +0000

Just looking at the mechanics of the Weaver Brothers, you would think they are going to be more successful against RHB. The ability to go submarine to throw that slider against a RHB would suggest more success.

By: Dave Cameron

Dave Cameron — Wed, 10 Feb 2010 01:53:15 +0000

I don’t think the evidence supports your theory.

Weaver, BABIP vs RHBs, career:

2006: .219
2007: .316
2008: .339
2009: .242

If there’s a repeatable skill there, I don’t see it. And, of course, I’m sure you won’t argue that he has a repeatable skill of BABIP prevention against LHB, considering the .307 career mark he’s amassed against them.

By: Eric M. Van

Eric M. Van — Wed, 10 Feb 2010 00:09:59 +0000

Weaver may be the worst possible example, seeing he’s the only pitcher in all of MLB that I’m willing (based on pitch/fx data) to argue has a true BABIP skill.

He has an unusual motion in that the upper arm is very much three-quarters but the forearm is vertical, resulting in a large rise and a small armside run, similar to a pitcher that comes right over the top (e.g., Okajima), whereas everyone else with his upper arm angle has the opposite. I believe batters unconsciously read the expected pitch movement from the upper arm angle and thus tend to be get under the ball and get it towards the end of the bat (if RH). The result is a lot of easy FB, especially to RF — a really high rate given the low % of swings and misses. The big platoon split comes from simply throwing the FB less often to LHB (perhaps for no good reason).

This hypothesis would lead you to expect that he’d have a larger-than-usual split by times around the batting order (as batters acclimated to the deception), and in fact he does.

By: BIP

BIP — Tue, 09 Feb 2010 23:12:01 +0000

Um, how does a pitcher give up 2.27 home runs per fly ball?

By: PhD Brian

PhD Brian — Tue, 09 Feb 2010 20:00:49 +0000

Could the quality of his defenders at certain positions during his career cause the much bigger real numbers? In other words, if he had a gold glover at third but an inept firstbasemen, then lefty and righty pull hitters where hitting into different situations and might see much bigger differences.

By: Travis L

Travis L — Tue, 09 Feb 2010 19:24:58 +0000

How do you know? While I’ve heard this theory as well, I’ve also heard the theory that a normal swing by a player generally takes them *across* the plate, thus conferring an advantage to the right handed hitter. In order for a lefty to have an advantage you can see, he would have to look like Ichiro, who clearly is heading to first as he hits the ball. But regular lefties don’t have the same swing finish profile, so i don’t think this issue is settled.

By: drew

drew — Tue, 09 Feb 2010 18:38:40 +0000

Speaking of HR/FB being one of least predictive metrics out there…

Check out the differences in Beckett’s 05 and 06 season (when he moved from the NL to AL).

His HR/FB rate when pitching away from Fenway blew up from .92 to 2.27.

By: drew

drew — Tue, 09 Feb 2010 18:22:35 +0000

Felix has similar issues to Weaver’s. Higher HR rate and BABIP in his righty/lefty splits.

By: AK707

AK707 — Tue, 09 Feb 2010 17:59:03 +0000

I wonder if weaver also induces LH GB’s to the left side more? Forcing hitters to go the other way to put balls in play maybe?

By: Nate

Nate — Tue, 09 Feb 2010 17:51:42 +0000

Just a quick head’s up.. you have a link to his “slits” page, instead of his “splits” page. The link is good, just the text for it that’s got the typo.