James Shields Loves Domes

by P Brady on Aug 4, 2008 8:00 AM EDT

James Shields is an enigma wrapped around good control wrapped around a fantastic changeup. Who also really likes domes apparently. For his career his OPS+ in domes is quite a bit lower than in open air stadiums. His K rates and Walk Rates are pretty similar but just looking at his Home/Away WHIP, something is very different:

via www.fangraphs.com

To put his Dome success in table Form:

Field	OPS+	BABIP
Tropicana Field	86	.280
Metrodome	147	.432
Skydome	84	.190
Open Air	114	.309

So why is James Shields more successful in domes? One theory is his changeup is less HomeRun prone in a dome and his splits seem to explain this, only having 33 HRs in 1144 PA in domes, while in open air stadiums having 30 in only 854. Also, his Hit Rate is considerably up. The BABIP's of the Skydome and Metrodome balance out to Trop levels, so I did not worry about it much. Maybe like a knuckleball, Shields's change is better suited for a controlled environment. This is all Speculation of course, but when we build the new outside stadium, it might be time to trade in Mr. Shields.

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So basically you are saying Shields pitches well at home. Well so do most pitchers and in fact Garza has splits even more extreme.

I just don’t see how you can split this up as dome vs open air when it looks much more like just a basic home and away split. The fact that there are three domes and in one of them he has extremely huge numbers should put up a major red flag. Then you also need to account for that one of the domes plays host to one of the more pathetic offensive teams in the league.

When in doubt remember Occam’s Razor

by matthan on Aug 4, 2008 8:44 AM EDT reply actions

I am going to agree

I think the the fact that the games are at home are of more significance then them being in a dome

by Sveet on Aug 4, 2008 9:35 AM EDT up reply actions

Plus the # of road domed games has to be very small compared to home domed games

The games at the trop easily dominate the “dome” numbers.

by matthan on Aug 4, 2008 9:45 AM EDT up reply actions

Or

he could be a vampire. Just throwing every possibility out there.

by GomesSweetGomes on Aug 4, 2008 11:59 AM EDT up reply actions

Wouldn't that be night vs day games then?

I think he is batman thriving in the bat cave.

by matthan on Aug 4, 2008 2:14 PM EDT up reply actions

I'm not sure

If we are talking about ‘Blade’ vampires, he could be fine with adequate sunscreen. If we are talking ‘From Dusk Til Dawn’ vampires, then you are correct.

by GomesSweetGomes on Aug 4, 2008 11:05 PM EDT up reply actions

The change-up theory

The only way to really prove that is to go through the pitch f/x of each game and see what pitch home runs were hit off change-ups.

Josh Kalk’s PitchF/X tool has Shields at six home runs this year (small sample) and only one is off the changeup. Last year they had Shields for six homeruns, this time none were off the change.

You could probably assume that less than half his homeruns allowed are off changeups. It is probably less than that but it’s hard to assume anything off such a small sample.

Good post, and it did provoke deeper digging, but there are too many confounding variables to pin the difference on one thing right now. I do wonder why some pitchers are significantly better at home.

by tallyray on Aug 4, 2008 10:06 AM EDT reply actions