He's been one of the best pitchers in baseball for the past 2 - 3 years it seems but I don't understand how. This is a guy that was readily available for the taking after 2 bad seasons (ERA's over 5 and 6 in those seasons.) When it was suggested here that the Reds trade for him to add to the rotation, nearly everyone balked at the idea, and I can't really say that I blame them.
Here's Cliff Lee's career starting at age 23:
129/125 GS, 741 IP, 765 H, 255 BB, 549 BB, 1.38 WHIP, 4.64 ERA, 94 ERA+
Those numbers end at his age 29 season. That's pretty much an average if not below average pitcher. Here are his numbers after he absolutely exploded and rebounded after that 6+ ERA year.
2008: 31 G, 223 IP, 214 H, 170 K, 2.54 ERA, 1.11 WHIP, 168 ERA+
He's had two similarly amazing seasons since then as well.
How has he done it? The guy was destined for career of mediocrity for nearly 6 seasons, going well into when he should have already hit his prime. Then in his age 29 seasons, he goes from being the definition of average to one of the top 5 pitchers in the game.