Of course Leon is not the major reason Sale, Price, Porcello and others do well. They were all good to great before he caught them.
He's not the biggest reason. I don't think anybody thinks that, but if the differentials are for real, then to me, Leon is worth keeping over Swihart.
I think Leon got burnt out when Vaz got hurt, but his defense was always good/better. His bat might not be as bad as .550 again, and that is pretty awful, but if Swihart and Vaz both hit .600 to .650, then one can certainly argue Leon's defense can make up .050 to.100 on offense.
I get the argument to keep Swihart: he's cheaper; he has more years of team control; and his bat, despite little evidence to support it, likely has more upside potential.
Do all those who want Swihart over Leon think these numbers are a fluke, over inflated in value or not valid?
Sale career ERA with...
2.42 Leon (1250 PAs against)
2.51 AJP (896)
2.98 Navarro (388)
3.02 Flowers (2227)
3.36 Phegley (363)
3.40 Vazquez (218)
3.53 Avila (449)
Sale's ERA is more than 0.50 better with Leon than anyone else, except AJP. I think his ERA with Leon is more than 0.60 better than his career ERA without Leon as his catcher. Even if you figure luck had something to do with it, if we can get a half a run better every 9 innings from Sale, that makes up for a lot of bad offense.
Price's numbers are different, since he joined the Sox near the end of his prime, but Price still does better with Leon over Vaz and Swihart.
2.83 with Leon (769 PAs)
4.32 with Vaz (113)
5.73 with Swihart (48- super small sample size alert)
These numbers are shocking.
Are they useless?