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September 5, 2012

Pebble Hunting

The Rockies' Rotation, Before and After

by Sam Miller

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In June, you'll recall, the Colorado Rockies announced that they would be going to a four-man rotation, with each pitcher limited to 75 pitches. Josh Outman was the first pitcher to start in the new format, and the consequences of the Rockies’ shift were immediate: lots of people became aware that Josh Outman was pitching for the Rockies now. In the Seth Smith trade? You don’t say!

It’s still too soon to say what the four-man rotation—with 75-pitch limits on the starters—has wrought, and will wrou... uhh... whatever the heck the infinitive of wrought is. Work? It seems to be work. Wrought seems to be the past tense of work. Forget it.

What we do know is that the Rockies say they will continue this experiment into next season, so perhaps truth will emerge. In the meantime, we know this: the Rockies allowed 5.74 runs per game before the switch and 5.32 runs per game since. Done! Fixed! Go away Ervin Santana, teams need only four starters now.

Except that it’s obviously not that convincing. Some regression from 5.74 runs per game was already likely. The Rockies probably wouldn’t have made this move if they weren’t performing at a level far below expectations. They’ve also made plenty of personnel moves, so it’s a comparison between two different groups of pitchers. And 0.4 runs per game isn’t all that much. The Rays and the Mariners, for instance, will likely each have bigger first half/second half splits than that, when it’s all done. 

I was curious, though, to see where in the pitching staff the four-man format would bend or break. As Colin Wyers noted back in June, the rotation is just the front of the staff; any innings shirked by starters must be picked up elsewhere. So the Rockies plan could:

a) work, by removing the worst starting pitcher and by keeping starters’ workloads manageable and by keeping starters from getting hit the third time through the order, or
b) fail

and if it failed, it could
a) fail because the starters struggled on short rest, or
b) fail because the relievers picking up the middle innings would be worse than the starters, or
c) fail because the relievers picking up the middle innings would no longer be available in the late innings, and the relievers picking up the late innings would be worse and/or exhausted.

In other words: the Rockies could get worse early in games, or in the middle of games, or late in games. So, with the massive SSS caveat, let’s see how many runs, on average, they have allowed in each inning:

Inning Before After
1 0.78 0.74
2 0.4 0.46
3 0.97 0.66
4 0.82 0.56
5 0.78 0.93
6 0.6 0.44
7 0.62 0.47
8 0.43 0.72

So there’s a table. The first two innings are basically a push. The next two benefit the post-switch Rockies. The fifth, sixth, and seventh are kind of a mixed bag, and the eighth breaks dramatically in favor of the early-season Rockies. I left out the ninth for a few reasons, mainly that most ninth innings that matter have been handled the same way before and after the switch, but there’s no real difference there, either.

Could we explain these differences? Of course we could. There are ways to build a narrative around any result. We’d say that the Rockies do better in the third and fourth innings now because their pitchers aren’t holding a bunch of energy in reserve, and because the worst starter has been excised from the line. We’d say they do better in the sixth and seventh because they are turning to fresh relievers, rather than pushing their starters through the opposing lineup for the third or fourth time. We’d say they struggle in the eighth because the set-up portion of the bullpen has been spread thin by needing to cover the sixth and seventh innings, and because there are no dominant starters pitching dominant starts finishing the game. These are the narratives we would use, and they’re tempting because they’re exactly the way this plan is supposed to work if this plan works. Of course, there are easy narratives that could have explained the exact opposite results. It’s way too early to say this plan works, or doesn’t, for any reason, and that chart is a good 100 games shy of what I’d want to put my faith in.

Other notable parts of the Rockies' rotation so far:

• They are actually going with a five-man rotation at the moment. Since Jhoulys Chacin returned from the DL three starts ago, the Rockies have kept Tyler Chatwood, Drew Pomeranz, Jeff Francis, Alex White, and Chacin on a traditional schedule, but with the same 75-pitch restrictions.

• The 75-pitch restriction is, and has been, a bit overstated. The Rockies starters have actually averaged 76 pitches per start since the switch; there’s a 92, an 89, a 97, and a 91 mixed in there. There was an 18-start stretch in July in which the Rockies' starters—well-rested because of the All-Star break and off-days—topped 80 pitches 13 times.

• Rockies starters have averaged 4.44 innings per start, down from 5.09 innings per start before the switch. They have actually been, as a group, pretty much unchanged. They have thrown strikes on 60.8 percent of their pitches (up from 60.5 percent), struck out 6.3 batters per nine (down from 7.1), walked 1.78 batters per nine (improved from 1.88) and allowed 1.5 homers per nine (from 1.6). But, of course, the starting rotation has changed plenty since then, and continues to change. Only three pitchers have made at least five starts in each format: Alex White, Christian Friedrich, and Drew Pomeranz. White has been quite a bit worse. Friedrich has been somewhat worse. Pomeranz has been a bit of everything: fewer walks in the new format, more homers, lower BABIP, more runs. Sample size strikes again.

Sam Miller is an author of Baseball Prospectus. 
Click here to see Sam's other articles. You can contact Sam by clicking here

15 comments have been left for this article. (Click to hide comments)

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Wrought havoc? Will Wreak havoc?

Sep 05, 2012 04:56 AM
rating: 0
BP staff member Sam Miller
BP staff

This is discussed various places online, such as here,
but I'm still not sure I'm clear on it. It seems that wrought is two things: An archaic (but correct) past participle for work, as listed at dictionary.com: bit.ly/OOGobT
and an incorrect past participle for wreak. Wreaked, not wrought, is the correct past participle for wreak.

Sep 05, 2012 05:55 AM

Wrought iron. So, the for-man rotation has wreaked?

Sep 05, 2012 08:02 AM
rating: 1
John Carter

You are so fun and astute, Sam. I think Goldstein can be replaced by a few scout/writers as it appears to be the plan. However, providing relevant baseball content with as much humour as Jason and you do, is special.

If your nominated table narrative is correct, then it seems Colorado just needs to replace their 5th starter with a high quality set-up man.

Sep 05, 2012 06:59 AM
rating: 0
BP staff member Jason Wojciechowski
BP staff

Gee, thanks!

... oh, you meant PARKS?


Sep 05, 2012 09:21 AM

I bet Collete was thinking it was him. . .

Sep 06, 2012 09:34 AM
rating: 0

Cool stuff, Sam... I wonder also if there could be a minute effect on runs scored per game BY the Rockies since they probably have been giving ever-so-slightly more at-bats to pinch hitters instead of pitchers as a result of removing their starters earlier...

Sep 05, 2012 07:16 AM
rating: 0
BP staff member Sam Miller
BP staff

Over a long enough time period a small gain should show up, but probably quite limited. Colin mentioned this in his piece in June, when he pointed out that the extra pinch-hitting appearances would come from the bottom of the bench, not the better pinch-hitters, who were already being used.

Sep 05, 2012 07:27 AM

Long term, that could be a definite benefit of the plan. But for right now, the Rockies have actually been playing with a short bench for much of that time frame (due to injuries), and you'd be shocked at how often relief pitchers are getting at-bats.

Sep 05, 2012 07:53 AM
rating: 0

Sam, I really appreciated your look at this. Over at Purple Row, us Rockies fans have been mixed on this project simply because it appears to be thrown together with loose pieces of other ideas. The first month was a constant shuttle of pitchers between AAA and MLB, into and out of the bullpen, etc.

That said, since July 25 there has finally been a firm plan. The Rockies rotate four starters on a loose 75 pitch count, then rotate three piggyback relievers on a 50 pitch count. While your conclusions suggest that the Rockies have been using their back end arms to help support the middle innings, that's not really the case.

Your idea inspired me, so I took the data a step further from that date. Having such a small sample size dampens this data, but I found it interesting.

These are the Rockies' pitching by inning since July 25 compared to 2012 NL average. These numbers are NOT park adjusted.

Rockies pitching since 7/25 vs NL Average

1st: +0.29 runs
2nd: -0.02 runs
3rd: +0.01 runs
4th: +0.01 runs
5th +0.11 runs
6th: -0.03 runs
7th: +0.01 runs
8th: +0.45 runs

The 8th inning numbers are a direct result of rookies like Will Harris and Edgmer Escalona (fresh out of AAA) pitching in the 8th inning, as well as Matt Belisle having two bad outings.

In this small sample size, the Rockies have actually been at least league average in Innings 2-7 since firming up the rotation idea. If you consider these numbers are not park adjusted, you could argue that the Rockies ragtag group has been better than league average over that span.

I don't know if this means anything at all, but I find it fascinating. Again, thanks for your work.

Sep 05, 2012 10:19 AM
rating: 0
BP staff member Sam Miller
BP staff

Definitely fascinating, and I trust a Rockies follower more than myself to see these patterns. I can't wait until enough games have passed to try this piece again.

Sep 05, 2012 11:04 AM

Yeah, as a Rockies fan this season has been a beautiful disaster.

Part of me thinks they are insane, but mostly I want to see this experiproject given a fair chance. The front office has said it'll be continued into 2013, so we'll get to see what a pitching tandem offseason and spring training looks like.

Can't wait.

Sep 05, 2012 12:32 PM
rating: 1
Richard Bergstrom

The word for 2013 is they'll keep the four man staff on a 75 pitch limit, but they'll assign an "opposite handed middle reliever" with a 50 pitch limit for each day as well.

Sep 07, 2012 11:03 AM
rating: 0

Wring. You wring out the washcloth, but if its overwrought, it's bad for the cloth. That's what I thought, anyway.

For fun, I switched the before and after columns in your chart to see if I could build a narrative around the opposite result. In that world, the first two innings are still a push. The 3rd and 4th are worse, since the starters are getting tired after the lost rest day. The 5th is better because they're bringing in a shiny new reliever, but then the 6th and 7th get worse because that reliever is getting overstretched. Then the 8th gets another new reliever, so improves again.

Sep 05, 2012 11:41 AM
rating: 4
BP staff member Sam Miller
BP staff

Nailed the narratives!

Sep 05, 2012 12:17 PM
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