August Starting Pitching AL Overachievers

There are a few pitchers that stand out as overachievers in August with numbers that are not likely to hold up down the stretch in the final month of the regular season. These four American League starters may be worth avoiding or considering fading in upcoming starting efforts as the solid ERA results are hiding some red flags in the peripherals. 

Nick Martinez – Tampa Bay Rays

Martinez has been one of the best stories in baseball, an All-Star at 35 after bouncing between Japan, San Diego, and Cincinnati, and he's carrying a 2.93 ERA with a sparkling 1.10 WHIP. The trouble is the skill set behind it: a strikeout rate around 14-15% with a walk rate under 5% is an extremely low-margin profile, and his .264 BABIP and 85.2% strand rate are doing enormous work to keep the ERA where it is. His SIERA has sat close to 4.80 for most of the summer which is a staggering nearly two and a half runs higher than his actual ERA, the largest gap of any starter in the league at one point this season. Soft-contact command guys can run hot for a long stretch, but a profile this light on strikeouts leaves almost no cushion if the contact management slips even a little in September. The Rays have a difficult final month schedule that includes the Braves, Red Sox, Yankees, and Phillies as Martinez could become a question mark for the postseason rotation. 

Walbert Ureña – Los Angeles Angels

Urena has been one of the more interesting stories in the Angels rotation, sitting on a sub-2.70 ERA with a 97-plus mph four-seamer and a sinker that generates a ton of grounders. The double-digit walk rate and modest strikeout numbers in the minors were always the concern, and that's shown up in the majors too as he's been living off a .257 BABIP and a single-digit HR/FB rate that won't hold at this level forever. There's a real skill spike here worth taking seriously; his expected ERA based on actual contact quality is meaningfully better than his SIERA suggests, pointing to a genuinely improved 14% line-drive rate rather than pure fortune. Still, a starter with consistent double-digit walk rates is always one bad week away from a blowup, especially as opposing lineups continue adjusting to him for a third and fourth time through the league. The Angels don’t have much to play for in the final month as the lineup and bullpen support could grow weaker as well. 

Tanner Bibee – Cleveland Guardians

Bibee is the cautionary tale that has already played out. When we flagged him in July sitting on a 3.89 ERA against a FIP well over a run higher, the home-run issues and contact-management gap were the concern, and sure enough, his ERA has since climbed into the mid-4.00s, with a brutal seven-outing stretch since the start of July that's pushed his season line to a losing record and an ERA north of 4.50. It's a clear example of exactly the kind of correction these gaps predict, and it's worth keeping in mind the next time a Guardians starter looks too good against the peripherals. Cleveland's pitching development is real, but it isn't magic. Bibee deserves better than his 5-14 record in decisions and he pitched well in a late August loss to the Royals. The Guardians are heading for a tough September battle in the AL Central and AL wild card races and Bibee isn’t a pitcher to count on in big games down the stretch. 

Brandon Young – Baltimore Orioles

Young has been one of the best surprise stories in the league, and his ERA has actually held up better than most on this list, but the cracks are showing. After sitting in the low-3.00s through most of the summer, his ERA has crept up to 3.38 with a WHIP climbing to 1.34 as his walk total has risen alongside continued modest strikeout numbers. His Statcast profile has also normalized with an .89.4 mph average exit velocity and 40.9% hard-hit rate now produce an expected wOBA of .319 against an actual .307. That's a reasonably encouraging sign, but it also means the version of Young that carried an ERA in the 3.20s is probably not walking through that door again. Young is a solid mid-rotation arm rather than the ace-caliber breakout he looked like in June. Baltimore’s staying power in the AL Wild Card race can be questioned as well with some close-game fortune in recent weeks.