#MLB Pirates Cardinals Sabermetrics ERA

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While the Pirates’ Trevor Williams has been impressive in the second half, indicators point to a September downturn

By Stephen Gugliociello

The Pirates’ 26-year-old right-hander, Trevor Williams, has found sustained success since the All-Star Break in mid-July. 

In his six second-half starts, Williams has twirled a 0.97 ERA, not allowing more than two earned runs in any start, and compiling a 3-2 record (the team is 3-3 in his starts). He’s thrown for 37 innings,facing 147 batters, and given up four earned runs (three home runs) during that stretch. 

However, that’s where the positive ends for Williams. Despite an 0.97 ERA in his last six starts, the advanced metrics tell a different story. Williams’ FIP is at 3.99, and his xFIP is 5.04. This means that if his defense was playing “league average” defense, his ERA would be nearly three runs higher per game (FIP), and if he gave up closer to the league average of home run to fly ball ratio, his ERA would be over 5.00.

For a more tangible stat, it’s as easy at looking at the strikeout-to-walk ratio is 1.9:1 (19 strikeouts, 10 walks). His strikeout average is 4.62 per nine innings. This low strikeout total means teams are putting more balls in play. While his defense has had his back to the tune of a .226 batting average on balls in play, he’s allowed a near-equal ratio of ground balls to fly balls. 

With more balls in play, 91.2% of contact has been against balls in the zone. Williams’ fastball velocity has decreased every season through his brief career -- it’s now down to a 90.4 MPH, and he’s throwing it at an extremely-high frequency -- 70.5%. This has contributed to the lowering percentage of swing and miss percentage, which is down to 7.3%. So while he’s in the zone frequently (1,366 strikes to 798 balls), Williams is showing he doesn’t have the gas to put it past hitters. 

Here’s a question for you: Can a good number actually be a bad number? During the second-half, Williams’ WHIP is just over 1.00 (39 baserunners in 37 innings). At a microcosm, if you remove the three solo home runs Williams has given up during this stretch, he’s allowed one earned run to 36 baserunners. As you saw with the FIP and xFIP numbers, an ERA with that many baserunners to runs allowed is not sustainable long-term.

Finally, let’s look ahead to tonight. Williams takes on the St. Louis Cardinals for the second time during this stretch. His first start against them on Aug. 5, resulted in a 2-1 loss for the Pirates and Williams. Williams only lasted 5 innings, giving up 9 hits, 2 earned runs, and strike out 3 on 90 pitches, including a home run to Matt Carpenter, who is having an MVP-caliber season. Again, stranded baserunners good, low strikeout bad, low inning total bad.

The Cardinals have been a team Williams has struggled against in his career. Of those who faced him, batters are hitting .368 with a .977 OPS. Williams’ biggest bugaboo has been Carpenter, who is 7-16 with 3 homers, 6 RBI, and 4 walks. Carpenter has  produced an other-worldly OPS against Williams of 1.613.