We can compare a pitcher's actual performance to win contribution to what his W/L record has been assigned to him.

While Bert Blyleven is the pitcher whose W/L record does not do him justice (shortchanged by 33 wins), Jacob deGrom is...

... already an outlier, with deGrom's W/L record shortchanging him 19 wins (and 19 too many losses), at 1/4 the career length of Blyleven.

Per IP, deGrom is the 2nd most hardluck case after Jim Beattie of the Mariners (and former GM of the Expos).

You can see the appeal of W/L records. It fairly represents the contributions of Maddux, Pedro, RJ, even Clemens and Seaver, basically the five best pitchers ever. So it works when it works over a career. Except when it doesn't. And it has failed spectacularly with deGrom.