I don't understand why so many people seem to think the Dodgers need pitching. No, Jason Schmidt doesn't appear to be the answer as the fifth starter, but as my colleague Tim Marchman explained in his own inimitable way on Tuesday, simply moving Jeff Weaver into the rotation would be enough, given the Dodgers' comfortable lead in the NL West (seven games entering Thursday's action) and the fact that teams only need four starters in the postseason.

The Dodgers have the second-best team ERA in the majors (behind the Giants), and the third-best relief ERA in the game (3.37). According to Baseball Prospectus' win-expectancy-based metric WXRL, the Dodgers' bullpen has been the best in the major leagues this. True, they've lost Ronald Belisario, who was having a fine season before a drunk-driving arrest and elbow trouble derailed him, but Belisario was just sixth on the team in WXRL and the other top seven Dodgers relievers in that category remain on the 25-man roster.

So why did they just trade two solid prospects to the Orioles for closer George Sherrill?

I expect there are two reasons. First, Joe Torre likes to have a lefty in his bullpen and rookie Brent Leach has had a rough July, giving up a total of seven runs in four of his last seven outings for a 31.50 ERA over that short span. Hong-Chih Kuo only just returned from three months on the DL due to elbow problems. Torre thus lacks a lefty he feels he can trust. Second, the Dodgers are eyeing another NLCS matchup against the Phillies, who just ratcheted up their chances of getting that far by adding Cliff Lee to their rotation. Three of the big guns in the Philly batting order -- Chase Utley, Ryan Howard, and Raul Ibañez -- are left-handed, and Howard is especially susceptible to left-handed pitching (.182/.265/.297 on the season vs. .322/.405/.695 against righties).

There's a certain logic to that, but it's tenuous. Good pitchers can get good hitters out no matter what arm they throw with, and good hitters can hit good pitchers no matter what arm they throw with. Utley, for example, is hitting .286/.407/.541 against lefties this year, a bit below his production against righties, but only a bit. Ibañez is hitting .310/.379/.680 against lefties this year, which is a bit better than his line against righties. Sherrill has been unbelievably dominant against lefties this year (.133/.200/.156 on the season, or 6-for-45 with just one extra base hit, a double), but the rejuvenated Guillermo Mota has been nearly as good, posting a reverse split with lefties hitting .188/.289/.250 against him (12-for-65, just four extra-base hits, all doubles). Lefties have also hit just .229/.309/.313 against Ramon Troncoso, whose slight reverse split is closer to even than Mota's more extreme split.

Given the Dodgers' lack of regular-season need for relief help and the fact that Utley and Ibañez are not intimidated by lefty throwers, it seems to me that the Dodgers have acquired Sherrill to stop Howard and lefty pinch-hitters Matt Stairs and Greg Dobbs, who unlike last year are now complimented by righty bench bats Ben Francisco and John Mayberry Jr.

The 32-year-old Sherrill certainly will have value beyond this season given that he'll remain under team control beyond this season and is well established as a reliable lefty reliever, but it's debatable how much more valuable he will be than the 26-year-old Leach or the 27-year-old Kuo, neither of whom is making as much as a half a million dollars this year.

So what did the Dodgers give up to avoid a replay of last year's back-breaking Stairs homer? Too much.

Steven Johnson is a solid if uninspiring right-handed starter who, at age 21, has continued to impress having just made the jump to Double-A. He's not a big loss for the Dodgers, who have a tremendous young duo in their rotation in Chad Billingsley and Clayton Kershaw and the money to fill in behind them with reliable veterans, and he's not guaranteed to make a dent with the Orioles, who despite their dreadful major league staff have a farm rich with pitching prospects. Still, he's a decent throw-in and adds to the pitching depth in the Baltimore system.

The reason the Orioles should be clicking their heels over this deal, and Dodgers fans should hot under the collar, is Josh Bell. He's not true blue-chipper, but as a 22-year-old switch-hitting third baseman who was hitting .296/.386/.497 in Double-A this season, he has a high ceiling and fills a big hole in their organization. Bell's defense at the hot corner could use some work, but he's already shown an ability to improve in the field. Meanwhile, he receives top marks for his power, which suggests he could carry first base should he need to slide across the diamond. With top young talent in the outfield and behind the plate, Bell gives the O's a big bat for their infield and gets them that much closer to a lineup that can swing with the big boys in the AL East. Similarly, the Dodgers just lost a player who appeared to be on his way toward filling an organizational hole, be it in the wake of the 35-year-old Casey Blake at third or in place of the disappointing James Loney at first base. For a player who projects as a major league starter and potential middle-of-the-order bat in the near future, the Dodgers didn't get nearly enough, nor did they address a significant need. Before this trade, a playoff exit would have been disappointing, now it will be unacceptable.