Poll 2015: Which Group of Pitchers Performs Better? – The Results

For the third year in a row, I decided to put together a little experiment during the all-star break. I took two groups of 10 starting pitchers comprised of those whose ERAs outperformed and underperformed their SIERA marks by the largest margins. Oddly, the poll results no longer show how many readers voted, but of those that answered the question “Which Group Posts a Lower 2nd Half ERA?”, 72.2% of you voted for Group A, the SIERA outperformers. This is actually an increase from last year, when just 61.1% of you voted for Group A! Have you learned nothing from reading my work?! Despite this group actually posting a very slightly higher SIERA than Group B, you felt that the magic would continue. Let’s find out the results and if the majority was correct.

I’ll start by reviewing how the SIERA outperformers did in each half:

Wow, what a difference one half of baseball makes! This group suddenly lost their runner stranding abilities and skills at keeping fly balls in the park seemingly overnight! They sustained some of their BABIP suppression magic, though most of that is due to Chris Young and Zack Greinke (offset somewhat by the inflated marks from A.J. Burnett and Yovani Gallardo). We know Young is always going to run a low BABIP and outperform his BABIP, but Greinke has not earned such a reputation.

Interestingly, the group’s skills declined in the second half, as their strikeout rate fell, while their walk rate rose, helping to push their SIERA well above 4.00. From a group that was composed of major mixed league assets to a group that actually hurt mixed league ratios is quite the fall from grace.

As a whole, they still outperformed their SIERA, but barely. Keep in mind that SIERA ignores home ball park and team defense, so assuming a pitcher remains on the same team, he should continue to benefit from or be hurt by each of those drivers of performance.

I asked another question in my original post, and that was “Which Range Will Group A’s 2nd Half ERA Fall Into?”. The 3.25-3.49 range garnered the highest percentage of votes at 31.3%, while the correct range of 4.00-4.24 was voted on by just 2.03%, garnering just the sixth highest number of votes! It seems pretty clear that everyone assumed at least some regression, but nowhere near as much as actually occurred.

Group B – The SIERA Underperformers, 2nd Half

Name	IP	ER	K%	BB%	BABIP	LOB%	HR/FB	ERA	SIERA	ERA-SIERA
Carlos Carrasco	75.1	25	32.5%	6.9%	0.242	74.8%	17.8%	2.99	2.51	0.48
CC Sabathia	67.0	27	18.2%	10.3%	0.292	81.2%	15.5%	3.63	4.51	-0.88
Drew Hutchison	52.1	35	16.5%	6.1%	0.315	62.9%	17.1%	6.02	4.43	1.59
Jeremy Hellickson	51.1	22	18.3%	7.1%	0.255	76.2%	16.7%	3.86	4.24	-0.38
Kyle Kendrick	39.1	32	14.6%	9.0%	0.333	64.8%	18.5%	7.32	5.04	2.28
Kyle Lohse	44.1	25	14.4%	10.3%	0.319	77.7%	14.8%	5.08	4.96	0.12
Matt Garza	49.2	32	16.2%	10.8%	0.323	66.1%	11.3%	5.80	4.96	0.84
Rick Porcello	71.1	28	23.3%	5.0%	0.333	71.6%	14.3%	3.53	3.31	0.22
Rubby de la Rosa	78.1	36	15.0%	10.0%	0.273	75.8%	12.8%	4.14	4.92	-0.78
Taijuan Walker	67.1	31	21.1%	4.8%	0.266	65.7%	12.9%	4.14	3.70	0.44
Total	596.1	293	19.6%	7.9%	0.290	71.9%	15.0%	4.41	4.14	0.27

Looks like this group wasn’t prone to allowing hard contact all over the field after all! Well, at least according to BABIP. The group’s BABIP declined to sit just above Group A’s, which was actually below the league average. Who would have thunk that this group would post a better than league average mark after a .319 BABIP in the first half?

They also had a better time stranding runners, though their LOB% over the second half was still just worse than Group A’s. Remember that part about the hard contact? You should, you just read it in the last paragraph. Well, HR/FB begs to differ. The group allowed an inflated, above league average mark in the first half, and an even higher mark in the second half! Every single pitcher’s HR/FB rate in the second half was above 11%.

Unlike Group A, this collection actually sustained their first half strikeout rate, but their walk rate ballooned. It resulted in a higher SIERA, just like Group A. And this group underperformed again, but the gap was significantly smaller, which is rather surprising given that crazy HR/FB rate.

The leading vote-getter to the question “Which Range Will Group B’s 2nd Half ERA Fall Into?” was 4.00-4.24, which earned 31.56% of the vote. The correct range was 4.25-4.49, which finished fourth with 9.84% of the vote. You readers correctly assumed much better fortune in the second half, though like me, we were slightly too optimistic in our expectations.

–

So to the 72.22% of you who voted that Group A would post a better second half ERA, congratulations, you were correct! But I bet it was still surprising to see how much the gap between the groups narrowed. In the first half, Group A posted an ERA 2.91 runs better than Group B! In the second half, it outperformed by only 0.25 runs.

It is always tempting to try to search for an explanation for why a pitcher has either outperformed or underperformed his underlying skills. There will always be pitchers who continue to do so all year, but it’s near impossible to name them ahead of time. As in, they don’t possess any special abilities. Some do, but it’s a very, very, small group (Chris Young is one of them).

So the best course of action is nearly always to try trading these pitchers when the gap between their ERA and SIERA seems to have peaked. It’s better to be too early than too late when trading them away. You could have traded Sonny Gray for CC Sabathia and your team ERA would have been better off! Better yet, you could have traded Gray for an elite hitter after his 2.04 first half, and asked for Sabathia as a throw-in. Heck, Sabathia was probably free in the free agent pool. Gray for Carrasco would have been a fun challenge trade offer that would have been accepted in 99% of leagues.

I stress this every time I talk pitchers. It’s tempting to look at that shiny or disgusting ERA and think that’s what the pitcher is. He’s not. He’s more like his strikeout and walk rates, coupled with his batted ball distribution profile. Those are the underlying skills. ERA is just the result of lots of events coming together, that involve many more players than just the pitcher. SIERA is where your eyes should land first, and then you could wander on over to ERA if you must.