The fourth in a series of at least four, on how close selected Dodger prospects are to the majors …

Rubby De La Rosa
RHP, 6-foot-1, 170 pounds, turns 22 on March 4.

Summary: We’re talking about him because he leapfrogged other Dodger prospects to become the organization’s 2010 minor-league pitcher of the year. De La Rosa impressed in a short rookie-ball stint in 2008 (47 1/3 innings, 51 strikeouts, 1.71 ERA) before a lost 2009 in which he managed only 16 1/3 innings and allowed 11 runs (while still striking out 22).

*Correction: The Dodgers informed me that there was an error in their media guide, and that De La Rosa was never suspended for violating the minor league drug prevention and treatment program. This post has been amended to reflect that.

But the Rubby-bandwagon got rolling again last season. De La Rosa came back strong at the start of 2010 with a 3.19 ERA and 55 strikeouts in 59 1/3 innings, then shot himself into the stratosphere of Dodger pitching prospects when he moved up to Double-A Chattanooga and had a 1.41 ERA in eight starts covering 51 innings (though his strikeout ratio fell to 6.9 per nine innings). At the two levels combined in 2010, De La Rosa walked 3.1 batters per nine innings. (Note: According to Fangraphs, his Fielding-Independent ERA was virtually the same at both levels: 3.12 vs. 3.22.)

For comparison’s sake: The Dodgers have had no shortage of starting pitchers make a quick impression in Double-A in recent years. Scott Elbert reached it in his age-21 season, but didn’t get a taste of the majors until a brief shot in 2008 and is still looking to lock in even as a reliever. Clayton Kershaw got to Double-A in the middle of his age-19 year, began his age-20 year at the same level before getting promoted to the majors, and hasn’t been back in the minors since he hit drinking age. Age is not be a barrier to a midseason promotion for a Double-A pitcher, but sustained excellence must continue, and that’s easier said than done.

Track record: De La Rosa’s ceiling is high enough for you to stick a flagpole. But with only 180 official innings in his minor-league career, spread out since his mid-2007 pro debut, it’s hard to say with any confidence what De La Rosa can do over an extended period of time. Chattanooga Lookouts radio broadcaster Larry Ward told Brandon Lennox of True Blue L.A. in August that De La Rosa had a fastball that could smell 100 mph, plus a secondary change and slider, while Keith Law of praised his stuff before the 2009 season. The watchwords, it seems to me, are consistency and endurance.

How close is he? Without the sextet of veteran starting pitchers the Dodgers have, we might have seen De La Rosa by the summer solstice. But with the team’s newfound starting-pitching depth, not to mention alternatives like John Ely and Carlos Monasterios as temporary stopgaps, De La Rosa is probably on track for a mid-2012 arrival if he maintains his current pace. As always, extreme excellence or awfulness could alter that timetable, as could a decision to shift him to the bullpen should the need again arise in Los Angeles this year.

Did you know? De La Rosa did not allow his first professional home run until 2010, his fourth professional season.