Vincent Carchietta | USA TODAY Sports

Give Jordan Montgomery credit: He settled down, pitched into the seventh inning and allowed the Yankees to hit their way out of a hole in Monday’s 9-5 victory over the hapless Athletics.

But what is good enough to win a game in late June typically won’t cut it in late October. Montgomery’s rough third inning — Oakland touched him up for five runs in the frame — continued a troubling trend. While the Yankees have kept winning at a torrid pace, their starting pitching has been lackluster for some time now.

The rotation’s ERA over the last 20 games is 4.64, according to some unofficial ESNY math. Its WHIP is 1.3 during this span, which starts with the early June series at the Twins. The Yankees are 15-5 during the stretch, but just 5-4 in their last nine.

Gerrit Cole has the best ERA of the group — at 3.57. Montgomery (3.85) is the only other starter under 4. Nestor Cortes’ struggles have been the most prominent — his ERA during the stretch has been 5.31 and he has only pitched into the sixth inning once in his last four starts. But Jameson Taillon actually has the worst ERA at 5.75 to go with a personal WHIP of 1.72.

Luis Severino has an ERA of 4.76 and a WHIP of 1.29. The other WHIPs: Montgomery at 1.05, Cole at 1.14 and Cortes at 1.37.

Baseball is baseball, obviously. There are going to be lulls. But if you take out the Cubs sweep and this win over the Athletics, they Yankees are 11-5 against likely postseason teams (the Astros, Blue Jays, Twins and Rays) and they gave up five or more runs five times. And they were lucky to get a split with Houston; the Astros outplayed them.

There was already reason to be skeptical about the rotation’s preparedness for October. Cole has been hit-or-miss in big games. Severino hasn’t been there since 2019. Montgomery’s lone postseason outing was in the 2020 bubble. And Cortes and Taillon have never pitched there. But if those were not red flags, this stretch should be. It’s yet another sign general manager Brian Cashman would be wise to add another starter by the trade deadline.

James Kratch can be reached at james.kratch@xlmedia.com

James Kratch is the managing editor of ESNY. He previously worked as a Rutgers and Giants (and Mike Francesa) beat reporter for NJ Advance Media.