Analysis: Evaluating the Reds starting pitchers

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The Reds have played 37 of the 60 games on their schedule. With the off day, it’s a good time to check in on the team’s starting pitchers, to see how they are performing. Seven pitchers have started games for the Reds. Sonny Gray has the most starts with eight. Tejay Antone the fewest at two. Here are their current stats.

What importance should we assign each of these columns?

Strikeout (K%) and walk (BB%) rates are the “fundamentals” that analysts talk about. They are the aspects of pitching over which pitchers have the most control. For the vast majority of pitchers, they tell you what you need to know. Strikeouts are a measure of dominance. Walks are a measure of command. When you want to evaluate a pitcher and isolate how he has actually pitched, dominance and command are of central importance.

Ground ball percentage (GB%) is somewhat under the pitcher’s control. It produces a relatively consistent pattern from season to season. There is no one way to succeed in pitching relative to GB%, but as a general concept, you want more ground balls relative to fly balls than fewer. Ground balls never go for home runs and seldom for extra-base hits. Fly balls do tend to produce home runs. Grounders produce double plays. Other things equal, a higher GB% is a plus.

Average Exit Velocity (EV) is a direct measure of quality of contact allowed. It tells you if batters hitting the pitcher hard or if the pitcher is keeping them off balance. Pitchers do have control over this within a narrow, but important, range.

Earned Run Average (ERA) is an out-of-date way to evaluate pitchers. It does a terrible job in quantifying what it advertises by name — the number of runs earned against the pitcher. It ignores the role of defense, parks, scorers decisions, opponent lineup construction, bullpen effectiveness and just plain luck on balls in play. That said, it’s a common, public-facing stat. But with all the information we have one or two clicks away, it’s easy to do much better than ERA. I’ve included it here not for its value but to put it side-by-side with better metrics.

Fielding Independent Pitching (FIP) takes the actual strikeouts, walks and home runs the pitcher gives up. The idea is those are the outcomes the pitcher has most control over. Defense, for example, doesn’t matter on home runs. FIP is scaled to ERA for ease of translation. FIP has been proven to be a better predictor of future pitcher performance than ERA.

Expected FIP (xFIP) is the same as FIP except instead of using actual home runs given up by the pitcher, it normalizes that number based on how many fly balls the pitcher gives up. The idea, once again, is to focus on what the pitcher controls. Home runs are a function of fly balls more than they are a function of specific pitchers. xFIP has been proven to be a better predictor of future pitcher performance than either ERA or FIP. 

Expected Weighted On Base Average (xwOBA) is a composite measure of how a pitcher has performed. It accounts for strikeouts and walks the pitchers give up. It weights different outcomes based on run creation (doubles have a higher weight than singles, singles higher than walks, etc.). Instead of using the actual outcomes on hit balls the pitcher has surrendered, it uses the average outcome for similarly hit balls. That factors out quirks of defense, parks, opponent lineup construction, bullpen effectiveness and luck. It fixes the problems with ERA. It’s scaled to rate stats like batting average or on-base percentage.

The bottom row shows the current MLB average for starting pitchers. Numbers highlighted in red are much better than league average. Blue numbers are much worse.

Analysis

Sonny Gray, Luis Castillo and Trevor Bauer have all pitched well. Notice how close the three are in xFIP, once all the confounding factors are eliminated. Castillo has an excellent ground ball rate. That control over contact quality shows up in his EV as well (93rd percentile). Bauer is in the 95th percentile in xwOBA, mainly due to his outstanding K% and BB%. The warning signs, if any, are walks for Gray and a low ground-ball rate for Bauer.

Anthony DeSclafani has been poor and there aren’t promising fundamentals as silver linings. In a way, DeSclafani’s subpar 2020 so far is understandable. He hasn’t benefitted from regular starts. The gaps between his last two were eight and ten days. He had the game against the Pirates where he was tipping pitches and gave up 9 runs in two innings. But, his strikeout rate and walk rates are almost the same as each other. Last year, his K% was 24% and BB% was 7%. The Reds have to hope that with regular starts, DeSclafani will move back toward his career numbers. There’s a good chance of that.

Wade Miley is who we thought, except for a higher walk rate. Miley doesn’t strike out many batters. He relies on suppressing contact quality. Miley’s 2020 K% and EV (97th percentile) back that up. His walk rate is 5 points higher than his career. And he’s hit a couple batters in 12 innings, too. Miley’s bottom line xwOBA, reflecting the balance of his strikeouts, walks and contact quality, is awful.

Tyler Mahle has five starts and one relief appearance. The numbers in the chart, except for EV and xwOBA, reflect his starts. Mahle right now is an average major league starter. When you look at his starts, it’s usually possible to find something encouraging (11 strikeouts, pitching strong into the 7th inning) but also things concerning (too many fly balls, inconsistent secondary pitches). His ground-ball rate is alarming. Last night, if you recall, he gave up several scary fly balls. Eventually some of those will turn into homers.

Tejay Antone has just two starts. The numbers in the chart reflect his entire body of 2020 work. In a word, Antone has been spectacular. Other than a slightly high walk rate, Antone has been elite. His EV is 93rd percentile. Antone’s xwOBA is in the 96th. His strikeout rate (although helped by his relief stints) ranks second in this group.

Keep in mind these samples are too small to have much predictive power. Instead of thinking about this data as “what the Reds have” or “what the Reds will have” consider it “what the Reds have had so far this year.”

Bottom line:

1. The top three have pitched largely as expected, as elite major league starters.
2. Anthony DeSclafani and Wade Miley have been big disappointments.
3. Tyler Mahle, youngest of the bunch, continues steady progress toward being a solid starter.
4. TeJay Antone has flashed a breathtaking ceiling. Watch his progression.

Featured image: https://twitter.com/Reds/status/1116408275656949761/photo/1