If you’re wondering what lefthanded first baseman Adam LaRoche will bring to the Red Sox, here’s an assessment from a respected, longtime major league evaluator:

"I like the move for the Red Sox. ... He’s real streaky [offensively] and an outstanding defender. ... Most of his bad at-bats come against lefthanded pitching ... He’s a rhythm hitter. If he’s a little off, he can look real ugly. If he’s right, he can get real hot. There’s no in-between with him. ... He plays the game with a very easy pace. Sometimes people criticize that because it can look lackadaisical. ... He’s not just a pull guy. He can go all over the field. There’s ability there. You can’t put up 25 [home runs] and 75 [RBI] every year and not have something.’’

As most everyone knows at this point, the Red Sox needed a lefthanded bat that could provide them with some thump from the middle of the lineup, whether it be from the No. 5 or No. 6 spot. In their last 21 games against righthanded pitching, the Red Sox are batting .221 with a .679 OPS. David Ortiz's overall decline, coupled with J.D. Drew’s sudden and worrisome ineffectiveness -- he’s batting .236 now -- left the Red Sox especially vulnerable against righthanders.

With LaRoche -- who is hitting .247 with 12 homers and 40 RBIs -- in the mix, you should expect Mike Lowell to get some time off against righthanded pitching with Kevin Youkilis shifting to third base. With lefties on the mound, LaRoche will likely sit with Lowell playing third and Youkilis remaining at first. If Ortiz goes into any kind of funk, the Sox could also work Lowell into the mix at designated hitter against certain pitchers, only because the time away from the field would take additional strain off Lowell’s hip. Youkilis also could DH if the Sox choose; ultimately, depending on matchups, the bottom line is that the Sox now have four players for three spots.

A few other notes from the deal:

• Financially speaking, LaRoche will cost the Red Sox approximately $3 million for the remainder of the season. LaRoche is slightly more than halfway through a one-year, $7.05 million deal, and he is eligible for free agency at the end of this year. The likelihood at this stage is that LaRoche is nothing more than a rental, meaning the Sox will likely allow him to leave following the season, after which they will be awarded some form of compensation in the draft.
• If you expected the Sox to make a blockbuster acquisition before the July 31 trading deadline -- and if you still do -- don’t hold your breath. While there may be a chance for another, lesser deal -- a lefty reliever, maybe? -- the Red Sox have no major needs beyond a lefthanded bat. An elite hitter or pitcher would require the Sox to part with a top prospect -- someone like Clay Buchholz, Lars Anderson, Michael Bowden, Junichi Tazawa or Casey Kelly, among others -- and the Sox have given no indication in recent years that they are interested in trading up to six years of service from a relative young, cheap player for one or two years of service an older and potentially overpaid one.
• LaRoche was quite outspoken when the Pirates traded Nate McLouth to the Braves earlier this season. That almost certainly had nothing to do with this deal, but it does indicate some passion from a player who has been criticized, as reported above for sometimes appearing "lackadaisical.’’ And we stress the word appearing.
• Of the two minor-league players the Sox gave up in the deal, shortstop Argenis Diaz has "a chance to be an everyday player,’’ according to the same evaluator from above. Diaz has a long way to go offensively but is seen as a gifted fielder who might give the Pirates some long-term insurance behind Freddy Sanchez and Jack Wilson, both of whom are free agents after this season. The question is whether he can hit, which evokes comparisons to Engel Beltre, the infielder whom the Sox sent to Texas in the Eric Gagne deal in 2007. The other player sent to Pittsburgh is a Class-A pitcher by the name of Hunter Strickland, on whom the above evaluator had little knowledge.