Every single person was too optimistic. Among individual guessers, Bolton came the closest, predicting that LaRoche would hit .275/.350/.495. Almost everyone predicted that LaRoche would have a slugging percentage over .500.
It seems to me that Pirates fans were too hard on LaRoche for his April (which was, admittedly, godawful) and perhaps too easy on him overall. LaRoche's overall .272/.345/.458 line isn't what we should hope for from a 27-year-old first baseman who was coming off a .285/.354/.561 year and had been treated like the second coming when the Bucs traded for him last offseason.
LaRoche hit .133/.255/.265 in April, which was terrible, and fans were justifiably upset, and in some cases unable to see LaRoche's early struggles as part of a larger picture. But LaRoche is a historically slow starter - he's never hit above .214 in April. (It was also surprising, though, that the worrying didn't take the form of familiar complaints about streakiness, since, in terms of week-to-week consistency, LaRoche makes Craig Wilson look like a Rolex Yacht-Master.)
I'm not sure why this is, but in every season LaRoche has had so far, he's been terrible in April and a bit better in May and June, and he really gets it going in July. That's what happened this year. The problem was that he wasn't nearly as strong in July through September as he was in 2006:
LaRoche's 2007 July/August/September numbers were very good, but he didn't make up for his slow start the way he did in 2006. So the problem with LaRoche's 2007 season wasn't that his April was a mess - it always has been so far, and that seems to be the cost of running him out there. The problem was that his entire year was a muted version of his 2006. Not only were the lows lower, but the highs weren't nearly as stratospheric.
After gnashing their teeth over LaRoche for much of the first half, nobody really said a whole lot about him in the second half. The final results, though, were less than compelling, and if LaRoche is going to play like this, he isn't going to be part of the core of a great team. The trade for LaRoche was still a success - he's still a lot better than whomever else the Pirates might have tried out there, Mike Gonzalez has Tommy John surgery earlier this season, and Brent Lillibridge didn't come close to justifying PECOTA's spreadsheet-love. But LaRoche now looks like a serviceable player, not the .560 slugger we hoped for when we got him.