Every scouting report on De La Rosa mentions his plus fastball, plus breaking ball, and developing change. He had success in the majors prior to tommy john surgery, and numerous pitchers have come back from tommy john surgery and pitched very well. Do you have any reason to doubt his ability other than the Dodgers traded him?
Rubby De La Rosa is the 6th starter and is the ideal 6th starter in that he has options and there is a good excuse for him to start the season in AAA but he has already proven that he is a MLB caliber pitcher.
If the season started today the rotation would be Lester, Buchholz, Lackey, Doubront, and de la Rosa in some order. Maybe DLR isn't game ready and Morales, Aceves, or some retread pitches the last spot for a while.
That's seven starting pitchers who are all major leaguers, some of whom are quite good major leaguers.
I thought I was delusional, so I went back to the stats.
Rubby de la Rosa has pitched a total of 92 innings in AA, mostly in 2010-11. He posted a 2.35 ERA despite walking 4 batters per 9 innings due to an unsustainable BABIP and a ridiculously low HR/FB rate -- and while the latter may be indicative of skill, the former assuredly is not. And yes, DLR posted a 3.64 xFIP in 10 major-league starts prior to his TJ surgery -- which is impressive, but I'm sure we could assemble a list of horrendous major-league pitchers who sustained such a level of performance over a 10-start stretch (particularly with the benefit of being on their first trip around the league, and only being asked to pitch into the 7th inning twice).
That's the sum total of DLR's minor-league experience above A-ball.
Don't get me wrong -- I'm highly optimistic that DLR will fully recover from TJ surgery. I'm much less confident than others that he'll be back to his pre-surgery self in 2013.
I also agree that DLR is an interesting prospect, and a surprisingly good return in a trade that was fundamentally a salary dump.
But I don't get why DLR's scant track record has multiple posters characterizing him a "proven major leaguer," or words of similar import. He is no such thing.
And as I said above, the Dodgers agreed to include DLR in a trade that almost certainly wouldn't have fallen apart if they'd insisted on substituting a different prospect in his place. That concerns me more than a little.