Prospect Retro: Joe Nathan
Joe Nathan was drafted in the sixth round by the Giants in 1995, out of SUNY Stony Brook. Originally a shortstop, he hit just .232/.320/.345 in 56 games in the Northwest League in '95. The Giants decided that he wouldn't hit much, so they converted him to the mound in '96. He made his pitching debut in '97, posting a 2.47 ERA in 62 innings in the Northwest League, with a 44/26 K/BB. His fastball was impressive, but his breaking stuff was below average at this point. He'd rate as a Grade C, with `higher potential' if he could refine it.
Nathan took a big step forward in '98, going 8-6, 3.32 in 22 starts for San Jose in the California League, with a 118/48 K/BB ratio. He was hit hard in four Double-A starts, going 1-3, 8.80. But overall it was a fine year, as he showed improved command of a 92-95 MPH fastball. His slider and changeup were erratic, but I gave him a Grade B- in the '99 book and wrote that I was "optimistic about his chances" to continue pitching well.
Nathan began '99 I Double-A, but was promoted to Triple-A after just two starts. He ended up spending most of the year with the Giants, going 7-4, 4.18 in 90 innings, showing impressive velocity. But his K/BB in the majors was just 54/46, warning that slippage was likely as the hitters adjusted.
Indeed, he was hit harder in '00, with a 5.21 ERA and another bad K/BB ratio. Injuries and command problems hampered him in '01 and '02, and he was something of a forgotten man by that point. He converted to the bullpen in '03, pitched well, then became the Twins closer in '04 after being traded to Minnesota. He's been a dominant closer ever since, one of the best in the game.
Nathan's minor league record was certainly interesting: he made rapid progress after converting from shortstop, probably too rapid: he needed more Double-A and Triple-A time than the Giants gave him. Many pitchers have been ruined by being rushed in a similar manner. But he's found his niche in the bullpen.