The pen was imploding before Sale & ERod went on the DL, and the addition of Eovaldi, who has gone as deep as ERod goes and middle/long relievers like Johnson, Velazquez and Wright have taken up the slack of lost starter innings.
I'm not saying the pen hasn't suffered, but we have won at a very high rate with Johnson, Velazquez and Wright starting in the place of Sale & ERod.
Right - and that is a pure rate stat with a minimum number of ABs. (502) The ERA title has a minimum number of innings (162, which Sale has not quite hit).
Now looking at the numbers, Sale's IP per start is not greatly lower than Verlander (6.0 vs 6.3). That amounts to about 10-11 innings over the season - again, not much. What really is more relevant is Sale being mostly a noncontributor for the last 2 months of the season. There was a ton of value created in the starts he did make - but that the team has benefitted from his success less frequently than Verlander and Kluber by a pretty wide margin DOES matter - enough to make this pretty close. Again, if Sale wins it is a perfectly acceptable and just result.