Yes, Frank Tanana and Charlie Hough.
Tanana, the guy who early in his career (probably before your time) put together four brilliant seasons in a row, on some really awful Angels teams.
14-19, 3.12 ERA, 180 Ks
16-9, 2.62 ERA, league leading 269 Ks
19-10, 2.43, 261 Ks
15-9, 2.54 (led the league) 205 Ks
Charlie Hough who has 216 career wins and a 3.75 ERA, and won a lot of games on really crappy Rangers teams. Not to mention he was a guy who you always knew would go out and give you solid innings.
Darvish (again, he's a good pitcher, never said he wasn't) is 35 years old and has a career record of
86-70 with a 3.54 ERA. He's won over 10 games only 4 times in 10 MLB seasons. His career high in wins in a single season is 16, his first season with the Rangers. And since leaving Texas, he's been pretty much a .500 pitcher.
As for Kevin Brown, I think you're forgetting his '92 season with the Rangers when he went 21-11 on a team that went 77-85.
I didn't even mention Jon Matlack, who was dominating before getting injured and went 15-13 with a 2.27 ERA in 78 with the Rangers, and despite falling off after getting hurt still finished his career with a 3.18 ERA
Jimbo Franchione