If he sticks around and plays a full season this year and next, he'll likely be third on the franchise wins list behind Niekro and Dierker.
In terms of quality over the period of time he's pitched, I'd take him over anybody else. Compare Roy's five seasons (2001-2005) to the five seasons when Richard was really good (1976-1980). For good measure, I'll throw in Mike Hampton (1995-1999).Pitcher W L IP SO ERA LgER Pct H/9 W/9 BR/9 K/9
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Richard 84 55 1239 1163 2.79 3.39 +21% 6.6 3.9 10.5 8.4
Oswalt 83 39 981 850 3.07 4.31 +41% 8.6 2.1 10.6 7.8
Hampton 67 39 985 669 3.39 4.05 +19% 8.8 3.3 12.1 6.1
"Pct" is the amount by which the pitcher beat the league ERA. By that measure, Oswalt has been considerably more impressive than Richard. Richard did pitch a lot more, though, which is partly a function of when he pitched, and partly a function of his durability. I'd still take Roy.