The Most Vulnerable Rotations in MLB

Every team starts the season with five starters, but the chances a team makes it through the season unscathed is minimal. From research performed by Jeff Zimmerman, starting pitchers who made 20 starts and pitched 120 innings the previous season have roughly a 40% chance of hitting the disabled list during the season. Eno Sarris added to Zimmerman’s work before the start of last season and found that teams have been averaging around 10 starters per season since 2011. That average did not change last season as teams averaged 9.6 starters per team. Even if the bar is raised to a minimum of five starts, teams averaged 7.4 starters per team in 2014, consistent with five-year average of 7.5 starters per team per season.

Attempting to measure pitching depth can be difficult. Jeff Sullivan took a look at overall depth last month, showing how many players were projected for at least one win according projections. Focusing on rotation depth the same way is a good way to look strictly at depth, but with the season upon us, we can see the potential impact of that depth by examining the dropoff from starters to their replacements. FanGraphs completed the Positional Power Rankings with the pitching split into two posts, one for the bottom half, and one for the top half. Without rehashing the entirety of both posts, here is the graph from those posts which should provide a base of expectations for a team’s rotation.


The power rankings are based on the FanGraphs Depth Charts, where the number of innings are picked by humans based on our understanding of how the season is expected to play out. Current injuries play a role as does the risk of injury for some pitchers who are not as likely to pitch a whole season. In every team’s projection, the top four pitchers all ended up with at least 130 innings pitched. That is fairly realistic as exactly 120 pitchers had at least 130 innings pitched last season. The fifth starter can vary greatly with the number of innings past number five dependent on how many innings are expected from the top of the rotation.

Given the innings projected for the first four starters in every rotation, determining depth by separating the top four pitchers from the rest of the rotation can bring some clarity to depth and a potential dropoff. The fifth starter is not likely expected to carry a heavy load on most teams, and could easily fall out of the rotation based on performance, health and the potential of the replacements in the farm system. Using WAR, like above, will provide a good combination of innings and performance, but in measuring depth, innings are the question mark and might not aid a useful answer. Using FIP should provide a good measure of the talent at the top of the rotation, and help determine how far a team will fall should they lose someone for an extended period of time.

Here is a graph showing the average FIP of the top four starters for every team.

average_fip_of_top_four_starters (1)

The graph above is a rough approximation of the positional power rankings. The top four teams are the same, albeit in a slightly different order with Kershaw factoring in heavily and Gio Gonzalez not factoring in at all. The bottom four teams are the same as well with the Colorado Rockies outlook in 2015 not looking great.

To attempt to make a determination on depth, using the next four starters should provide a pretty good idea of what teams are looking at if they have to make a move in their rotation. While some teams have very good fifth starters expected to make an impact this season, they are included as depth given that a good fifth starter is a luxury item that most teams do not possess. In the FanGraphs Depth Charts, the Washington Nationals were the only team to have a fifth starter projected to exceed 140 innings with only a handful of teams even pitchers expected to reach 120 innings.

As opposed to just looking at the fifth or potentially sixth starter, I am going down to eight starters because on average teams use between seven and starters for at least five starts every year. The remaining starts are likely to be divided among the sixth, seventh, and eighth starters anyway as teams try out different options for pitchers who might lack experience in that role.

Here is the average FIP for every team’s fifth through eighth starters.

average_fip_of_starters_5-8 (1)

With Gio Gonzalez listed as the fifth starter and Tanner Roark available if someone should falter, the Nationals depth appears prepared to aid the team if anyone should falter. The St. Louis Cardinals have a host of young options available to them and the New York Mets have Noah Syndegaard grounded for the moment. The San Francisco Giants have experience with Ryan Vogelsong and the potential of Yusmeiro Petit should the need arise, but the Cincinnati Reds and the Chicago White Sox do not appear to have a lot of help at the end of the rotation with Jason Marquis and Hector Noesi at the end of the rotation, although Carlos Rodon could perform better than his current projections indicate.

The last graph above is a good representation of who has the best depth, but does not necessarily say which team is the most vulnerable to a loss. Subtracting the FIP of the first four starters from the FIP of the last four starters helps tell which team’s projection could suffer the most if a top starter is removed from the equation.

difference_in_fip_from_starters_1-4_and_5-8 (1)

It would be easy to say that the best teams are the most vulnerable, but that does not look to be the case. The Reds and the White Sox have middle of the road rotations, but they are heavy at the top. The negative numbers from the Kansas City Royals and Miami Marlins show that those rotations could improve as the year goes on if they get meaningful contributions from Kris Medlen and Jose Fernandez, respectively. Of the top rotations, Washington, St. Louis, the San Diego Padres, and the Cleveland Indians look pretty good to weather any storms, but the same is not true of the Dodgers or the Detroit Tigers.

The Dodgers already have concerns about Hyun-Jin Ryu, and should anything happen to Clayton Kershaw, Zach Greinke, or Brandon McCarthy, the team could be in some trouble. They have a little bit of a cushion in the National League West, but they are already hoping Brett Anderson can pitch well. Relying on Joe Wieland, Brandon Beachy or Zach Lee for an extended amount of time could be problematic for a team expected to repeat as NL West champs and contend for a World Series title.

Craig Edwards can be found on twitter @craigjedwards.

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9 years ago

This is interesting, but it’s hard to say how valuable this exercise this is. Could you repeat this for the 2014 depth charts? Then you could compare those numbers to how the 2014 results varied from the projections.

Did depth (defined as average FIP for projected starters 5-8) actually have any relationship to the errors (actual-projected WAR) from last season’s projected starters? Or is this just an interesting exercise that doesn’t really tell us anything (useful) that we didn’t already know?

9 years ago
Reply to  someone

I agree. This is something that might make you say “hmmm” but it seems a bit rudimentary. First, I don’t know why you’d use projected FIP instead of projected ERA. Second, it would make sense to weigh the 5-8 pitchers depending on their projected innings. A crappy 8th pitcher just isn’t that big of a deal. You can’t compare that to your 5th starter or primary backup.

9 years ago
Reply to  someone

2014 would be a data point of 1 and wouldn’t be of any actual use. Injuries involve a lot of variance.

“Or is this just an interesting exercise that doesn’t really tell us anything (useful) that we didn’t already know?”

Oh I’m sorry, did you already know the average drop off each team would experience should one of their starting pitchers get hurt? Did you make a community post on this already?

This is a pretty silly comment. Nothing we read here is actually useful to us, as we don’t work for a team, and if we did we’d probably have better metrics than even FIP and fWAR.

I for one find it interesting to know which teams will be in the best/worst spot should they experience multiple injuries to their rotation, and there wasn’t a place where that information was organized before. The depth charts hold all that information of course, but it needed someone to take that information and organize it in a way that shows us which rotations would experience the steepest drop offs.

9 years ago
Reply to  BMarkham

Are you Craig’s mom or his dad?

9 years ago
Reply to  TKDC

He wrote for my favorite Cardinals blog before he came here. But I would have wrote this response regardless of which of the fine fangraphs writers wrote the article, as it had much more to do with the stupidity of the comment than the author he was critiquing.

Maybe I just get too annoyed at stupid comments, which I admit is my own shortcoming since I voluntarily read them.

Craig's dad
9 years ago
Reply to  TKDC

I am. Nice job, Son.

oh Hal
9 years ago
Reply to  BMarkham

I guess you found use in the post in fulfilling your interest. I doubt it has much predictive value though. I looked through the Fangraphs depth chart and despite having a hundred or so people on the payroll, it doesn’t seem to reflect that.