Citi Field is indeed a pitchers' park, as detailed here. But historically, pitchers' parks have disproportionately produced winning teams. It's no excuse. https://www.wsj.com/articles/even-the-mets-home-stadium-is-mocking-them-11554292802 …
*Some* Mets pitchers have benefited from Citi Field. Home/road ERAs since 2015: de Grom 2.22/3.01 Syndergaard 2.66/3.32 Lugo 2.10/4.70 (!) Gsellman 4.17/4.73 Harvey 4.43/4.94 Colon 3.45/4.13 But: Wheeler 4.06/3.89 Matz 4.00/3.90