Will Middlebrooks has started off really well in the first 10 games of his MLB career. Just to play devil’s advocate, though, check out the list of players in the last 20 years to have at least 4 HR in their first 10 career games:
Bucky Jacobsen famously never played another season, and numerous other guys like Mark Quinn, Brant Brown, Kevin Roberson had pretty short and unremarkable careers.
Of course, Middlebrooks has hit very well so far, well more than just a few homers. AND the number of star and superstar players on this list is high enough that it’s pretty good odds (if Middlebrooks is “only” as good as Geoff Jenkins, he’ll still be a great player for a bunch of years.)