Why The Six-Man Rotation Would be a Bad Idea for the Rays in 2012
With Matt Moore signing an extension that could keep him with the Rays until after his dirty thirty birthday party we should be able to look forward to him starting the season in the Major Leagues. This is excellent news for all, but one man as either Wade Davis or Jeff Niemann will most likely be bounced from the rotation to make way for the young gun. Ignoring a potential trade, because neither player carries a ton of trade value and we haven't gotten many bites on the line, this leaves six pitchers for five spots. Or does it?
In 2011, the Rays briefly went with a six-man rotation as they were again vexed with too many good pitchers for too few spots. There are pros and cons generally bandied about to the worth of the six-man rotation as it gives a chance to spread innings out. This can help ease guys into a full-time role in MLB while potentially allowing pitchers better durability due to increased rest between starts. You can take this a step further by suggesting that perhaps Mr. Maddon would be more willing to let a guy throw an extra 10-15 pitches per start that can help a guy go an extra half to full inning per apperance. These things sound well and good, but the primary reason why this set up is less than ideal is due to the fact that the spreading around of innings means that your best guys are going to be seeing proportionally less innings as the four through six guys bite into the overall available innings.
We can look at this using some projections as well as a rudimentary expectation of number of starts based on how the schedule lines up. As an aside, I put this together that looks at the Rays daily schedule with opponents, win percentage from a year ago, and which starter you'd expect to go that day.
As we get closer to the season and it's easier to project how teams will do next year we can update the winning percentages to get an idea of when the toughest and easiest parts of the schedule will be. To that end, here's a chart with a 10-game moving average of 2011 win percentages to get a basic idea of these things:
A rough start leads into a relatively easier portion of the schedule with the easiest part of the year coming in late-July to mid-August being the pastrami between two rock-hard buns of difficult games.
You can see in our table how I've laid out the rotation throughout the year. The only re-working comes post-All Star Break, which doesn't necessarily reflect reality, but I think it suits our purposes here. The next step is to project each of our pitchers. Again, we can use a Marcel technique here to get a gauge of how each pitcher should be expected to perform in 2012. Hellickson has only a little over one year so I'd put less stock in his projection than the others. Moore's numbers come from Fangraphs Reader Projections which are better than nothing, but not by much:
I'd expect Moore to finish a bit higher as it won't be all sunshine and rainbows in his first go around, but we'll work with these numbers going forward. For this exercise we're mostly concerned with Innings, ERA, and FIP, though I included the others to give you a well-rounded perspective of how you would expect these guys to perform in the upcoming season. We can count up the number of expected starts from the framework above and get:
# 5-Man 6-Man
1 34 28
2 32 28
3 32 27
4 32 27
5 32 26
6 0 26
The next step is to tie the projections to our expected number of starts:
In this scenario, we expect Shields to make 34 starts at 6.9 innings per which gives us the 234.3 innings and so on down the line. At his projected ERA of 3.90 he would yield 101 earned runs. If we add this up for everyone then you get 1,026.2 innings for the five starters allowing 408 runs. This is good for a starting pitcher ERA of 3.58 with a FIP of 3.89. Of course we can't forget that there are nine innings to a game so we subtract the starter's innings from 1,458 (162 x 9) and are left with 431.8 for the bullpen. A straight up guess of 4.00 ERA/FIP allows us to see that all Rays pitchers would combine for an ERA of 3.70 and a FIP of 3.92 giving up an even 600 runs (the Rays allowed 577 in 2011 to lead the American League).
We can compare this figure to the extrapolated six-man pen rotation that includes Wade Davis and see that the starters actually go less innings, overall, with a slightly higher ERA/FIP. With the extra bullpen innings thrown in we see that the extra innings to your best performers is slightly more optimal than spreading the innings around with an extra guy. However, we can tweak this model a little bit as Wade Davis wouldn't just cease to exist in this version of a five-man rotation. Going a step further, you also would expect improved results if he's coming out of the pen as virtually all starters perform better coming in mid-game. Let's say that shaves off half a run from his ERA and half a point from his FIP. Additionally, we hypothesized earlier that pitchers may have a longer leash so let's also tack on another half inning per start for each guy:
Our new model shows virtually the same exact results for the five-man rotation with Wade Davis assuming 60 innings out of the bullpen's share. ERA would be expected to drop 1/100th of a point a.k.a. virtually nothing, while FIP would remain exactly the same. The story changes a bit when looking at the tweaked six-man rotation. Namely, we see that the six starters would combine for essentially 1,100 innings meaning the bullpen would only need to step up for around 350. Again, we see that the ERA/FIP numbers are essentially the same as the untweaked six-man rotation and still not as good as the five-man rotation that leans on the bullpen featuring Wade Davis.
Taking all of this into account, it's pretty clear that the Rays would be better served rolling with Wade Davis in the pen in 2012 than taking innings from Price and Shields in order to keep Davis in the rotation. What's your preference?