But the pitchers you list are anomalies. The average salary for a starting pitcher is 4.9 million. The average ERA for starting pitchers in the NL this year was 4.01. Jackson's ERA was 4.03. For 11 million, I'd expect more.
young pitchers make less and skew the average. zimmermann, latos, medlen, hellickson, etc. all make well below the league average of 4.9M.
veteran SPs make more. they've proven they are reliable. they demand long-term contracts. edwin got a 1-year deal.
it's just the way it works. i suggest being frustrated about our offense, harper's no-show, zimmermanns atrocious start, gio's 7 walks, or something that remotely matters.