Wins are the least important stat when it comes to a pitcher - see Loopers 14 wins 2 seasons ago. Whether he is in the AL or NL, a pitcher can't control run support - but when in the NL, he'll face a weaker lineup than in the AL and pitchers, in theory, will put up slightly better numbers when in the NL. I think you are either missing my point or I am doing a poor job explaining it. All things save for the DH held constant, if a pitcher moves from the AL to the NL, his numbers should improve. The improvement in his numbers will not, however, improve his overall chances of winning games. Therefore, you can't really use the assumption that a pitchers numbers will improve by moving to the NL to justify a contract or imply that there is a built in "fluff factor" to absorb a regression in ability due to age. The reason is because the team sees no real benefit from this. In theory, the pitcher will have better numbers but for the same reasons, will get less run support. In other words it washes out.