How’s Gabe Kapler doing these days with starting pitcher usage?

They say first impressions last forever. If that’s true, then we are all still hung up on the fact that Gabe Kapler pulls starting pitchers too early based on that disastrous Opening Day game where he yanked Aaron Nola after 68 pitches only to be rewarded by an ugly bullpen meltdown. The performance inspired much hand-wringing and some silly thought pieces about the Kapler way.

But now that we’re four weeks into the season, let’s look at what Kapler’s been doing in this regard. Does he still have a short leash with his starting pitchers?

Looking at the simplest measure, the answer is a clear no. So far, Phillies starting pitchers have averaged just over 5.5 innings per game. That’s not a lot, but it’s good for 6th most in the National League. The Nationals’ starters average the most, with just a tick under 6 innings per game, while the Marlins’ are the worst, at 4.9 innings per start.

With this ranking, it’s hard to argue that Kapler is doing anything outside the norm when he’s working his starters just above average for a National League team.

But let’s dig just a bit deeper here. It would seem to make sense that a team with a better starting pitching staff should work those pitchers deeper into games, while a team with worse starters would pull its starters earlier.

To measure this intuition, I used a rudimentary ranking system to compare where a team is in the NL in fWAR (overall starting pitcher effectiveness) and IP/G (innings pitched by starter per game). What this gets at is under- and over-use of starting pitchers. A team ranked 8th in fWAR in the NL and 8th in IP/G, for a rank difference of 0, is using their starting pitchers roughly in line with their comparative quality. But, if the 8th ranked team in fWAR is 1st in IP/G for its starters, it’s a good indication that the team is over-using the starters. And the opposite would be true — if the 8th ranked team in fWAR is 15th in IP/G, the starters might be under-used.

So how are the Phillies doing looking at the starters this way? While the team is ranked 6th in the NL in starting pitcher usage, the starters are 2nd in fWAR, tied with the Nationals at 2.8 (Dodgers lead the league at 2.9). Looked at this way, it appears the Phillies are under-using their starting pitchers given their quality so far.

Interestingly, most teams in the NL are within 1 or 2 ranking spots when comparing fWAR and IP/G, indicating that the starters are being used in rough relation to their comparative quality. Only 6 teams are further away than that, three at both ends of the spectrum. Here are those six, with their rank difference in parenthesis:

Over-used: Pirates (4), Cardinals (3), Cubs (3)

Under-used: Dodgers (4), Phillies (4), Rockies (4)

This is an interesting list. Are the Dodgers, Phillies, and Rockies making a concerted effort to under-use their starting pitchers (relative to their quality) in order to avoid the third-time-through-the-order problem and save the pitchers from injury and long-season-exhaustion?

Or, rather than quality of starters driving how long the pitchers should be used, which is the basic assumption of this comparison, maybe the causation arrow goes the other way? The Dodgers are the top-ranked NL starting rotation, the Phillies second, and the Rockies right in the middle at 8. Maybe they are doing well because they are being used less than they might comparatively be expected to? Fresher arms might equal better results.

At the other end, the Pirates (8th), Cardinals (6th), and Cubs (13th) are a collectively worse-ranked group of starting pitching staffs. Are the coaches throwing caution to the wind by sending them out deeper into games? Or is there, again, some causation here going from usage to quality - over-used starting pitchers will pitch worse?

It’s too early to draw conclusions, but this is interesting data to have in looking at what Kapler is doing so far. Looking just at innings per game, there is no doubt that Phillies starters are looking like a normal group of starters and that Kapler isn’t deviating that much from the norm. But, looking at quality too, he may be taking a particular approach to under-use his starters for strategic reasons.

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For those interested in the numbers and drawing their own conclusions, here’s the raw data: