LaRoche seems to have the first base job in hand and will have to play his was out of it. Is he Mark Grace, or only Doug Mienkiewicz? Or possibly Rico Brogna?
To get the last out of the way, he doesn’t appear to be remotely comparable to Brogna. Both were/are lefty first basemen with good gloves and middle-range power, but Brogna was a .269 career hitter with a .320 OBP; LaRoche should easily better that over his career. That’s not to say that he’s going to hit better than that as a rookie, but he’s got a good chance.
Reports are that Mientkiewicz is the lower range of LaRoche’s long-term projection, Grace the high end, and there’s less difference in the two than you might think — maybe five homers and ten doubles a year. I personally think LaRoche might be a slightly different player than that type. He did hit twenty homers last year at age 23, playing two levels. Mientkiewicz has never hit more than 18, and that at Salt Lake, one of the most hitter-friendly environments on Earth. Grace never hit more than 17 at any level. I think he might not be a .300 hitter like Grace, but on the other hand he might hit 25 homers a year, 30 in a good year. With his defense that should be good for the next 5-6 years.
I should point out that if he’s “only” as good as Doug Mientkiewicz, that’s not a bad thing to have and would make him the best first baseman the Braves have produced since… Gosh, I don’t know when. If we don’t count Klesko, he might be the best they’ve produced in Atlanta. Mientkiewicz isn’t a star, but if the Braves had him last year they probably would have beaten the Cubs. The Twins have other options, which is why their Mientkiewicz obsession hurts the club. The Braves are counting on LaRoche because they don’t have any better options.
It should be pointed out that (a) Mientkiewicz didn’t establish himself in the majors until he was 27, four years after his initial cup of coffee, and (b) LaRoche struggled on his promotion to high A-ball in 2001 and to AA in 2002 before finding his power on his second exposure to each league. So an adjustment period is possible. I don’t have a computer and a fancy projection system with a silly acronym, but I’m 95 percent sure that LaRoche will have a significant major league career. However, I think there’s a good chance — 25 percent, maybe — that he loses his job, and a 25 percent or greater chance he hits something like .270/.350/.400, which isn’t close to what you want from a first baseman. But he’s also got a good chance of hitting 20 homers and putting up a ROY-type campaign. We’ll see… I don’t think he really needs to be platooned, and I hope it doesn’t stunt his development, but getting some extra time off and not having to face the Randy Wolfs and Dontrelle Willises of the NL East can’t hurt his short-term chances.