Out of all the retired pitchers in MLB history, there are 2,191 who logged at least 400 innings through age 34.
Of that group, 317 fared so poorly that they had a career WAR value of less than 1.0 WAR through age 34.
With such a poor performance in a reasonably long trial, it’s no surprise that just 21 of them pitched in the majors from age 35 onward. Most of them were finished before they turned 30.
And of those 21 who did pitch at age 35 or older, only one ever had a season worth at least 3.0 WAR.