Phillies Star Nola's Heavy Struggles This Season Stem From Just One Thing

Can Aaron Nola turn it around for the Philadelphia Phillies?

May 3, 2025; Philadelphia, Pennsylvania, USA; Philadelphia Phillies pitcher Aaron Nola (27) throws a pitch during the second inning against the Arizona Diamondbacks at Citizens Bank Park. | Bill Streicher-Imagn Images

Aaron Nola has been a key member of the Philadelphia Phillies rotation for 11 seasons now. The quintessential workhorse in MLB today, he has been named an All-Star once, finished top-five in National League Cy Young voting twice, and top-15 in NL MVP voting once.

With the success that he has had throughout his career, it is very uncharacteristic of him to be eight starts into the year and hold a 4.89 ERA. While he has finished full campaigns with ERAs above 4.00 before, 4.89 would still be the highest mark of his career in that metric, and he also currently holds a career-worst 86 ERA+ across his first 46 innings this year.

You do not expect to see Nola struggle as he has to this point in the year. This is the same pitcher who led baseball in bWAR in 2018 with 9.7. He has topped 180 or more innings a year, every (full) year since 2018. Why is he struggling this year?

Why Aaron Nola is Struggling in 2025?

It all boils down to one thing: who is behind the plate for his starts.

No, not the umpire, who the catcher is. Through Nola's eight starts so far, they have been split evenly between J.T. Realmuto and Rafael Marchan. The results have been drastically different.

With Realmuto behind the plate, Nola has pitched to a 2.49 ERA across 25 1/3 innings with 22 strikeouts. He has also held opposing batters to just a .228/.276/.402 line with a .678 OPS and only five walks.

With Marchan calling his pitches, however, Nola has pitched to a 7.40 ERA across 20 2/3 innings with 28 strikeouts. While he has struck batters out at a higher clip with Marchan as catcher, opposing hitters have still been able to bat .306/.392/.494 with an .886 OPS and 10 walks.

Nola is not the only Phillies' pitcher to struggle with Marchan behind the plate, either. Cristopher Sanchez has been a dark horse Cy Young candidate this year, carrying a 2.27 ERA across his six starts when pitching to Realmuto. It's a 6.35 ERA for Sanchez in his one start with Marchan behind the plate.

If Philadelphia wants Nola to perform as one of the best pitchers in Major League Baseball as he is capable of doing, having Marchan catch for him is not the answer.