That is (as people have said above), it’s fairly easy to get a replacement-level reliever that will give you a ~4.5 ERA. So the only difference (on a season-wide scale) between the starter going 5 IP, 0 ER and 7IP, 1ER is having to waste one (or two) bullpen arms in the process of getting 7 innings, as both will, on average, leave you with 1 run scored per 7 innings.

So the question is what is the value of not having to have that extra bullpen pitcher? I’d say that my initial thought is that it’s a fairly negligible effect that will exponentially grow with the number of starters; if you have 4 starters that regularly go deep into games, having one starter give you 5 very good innings would be fine, whereas a team with 5 starters that all go 5 innings per start will destroy your bullpen fairly rapidly

]]>Of course 2 runs in 5 innings leaves your team a chance to win.

Even if your bullpen ERA is a mediocre 4.5 (or lets just say RA/9 innings), then over those 4 innings you could give up 2 more runs on both a mean and probable median basis

If your opponent scores 4 runs a game, you have given your team a non trivial chance.

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