“What’s the matter with Daisuke Matsuzaka?” is how MLB.com’s Ian Brown begins his recap of tonight’s Red Sox game, adding, “That question, as difficult as it is to answer at the moment, is more mysterious than haunting for the Red Sox at the moment.”

I beg to differ. It’s not mysterious at all. Julio Lugo is what is the matter.

As I’ve been trying to explain to people since last summer, when I had the distinctly painful experience of watching Lugo “play” 50 or so games for the Dodgers, Julio Lugo is not a good player. Sure, he put up some gaudy numbers in Tampa Bay, far, far from the klieg lights of actual playoff contention, but you really have to watch Lugo every day to see the little ways he hurts teams with his bad decisions on the basebaths, his ill-advised positioning and hesitant play on defense, and his bafflingly low-quality at-bats in key situations (eg doubles down the line with nobody on and two down, strikes out on three straight swings with and a man on third and no outs).

Tonight, by my count, Lugo single-handedly cost Matsuzaka five of the seven runs he allowed on five terrible plays, only one of which was ruled an error (another was initially called an error but later reversed and called a hit).

In the first, after Matsuzaka walked the bases loaded, Lugo in explicably went for the out at third rather than turning a double play. A few minutes later, Lugo let Kenji Johjima’s easy grounder glance off his glove for his only official error of the night. Finally, Lugo let Yuniesky Bentancourt’s pop-up glance of his glove for what should clearly have been another error, but just because he had to run a bit out into the outfield they later said it was a hit.

So while Matsuzaka was certainly not on his game, he basically had to get 6 outs in the first innning thanks to Lugo.

But Lugo was not done causing harm. After Daisuke settled down and breezed through the next three innings, he ran into a bit of trouble in the fifth, walking Raul Ibanez and giving up a single to Richie Sexon.

Re-enter one Julio Lugo.

Jose Guillen hit another little pop-up behind shortstop. Lugo started after it, then hesitated, then started up again before going into a pathethic little slide as the ball dropped at his feet. They scored it a hit as a run came home.

Daisuke then got Johjima to ground out (to first and not short, thankfully), and then Bentancourt hit a slow, easy grounder straight at Lugo, who took his time, fielded it, and then threw high to first forcing Youkilis to leap up off the bag. Again, this was somehow inexplicably called an “infield single.” Seven “earned” runs for Matsuzaka in five innings, although Lugo actually earned five of them.

This isn’t the first time Lugo helped undo Daisuke. You may remember that Matsuzaka lost his third start of the season in heartbreaking fashion when he was outdueled by Gustavo Chacin 2-1. Much was made of how Matsuzaka got “rattled” in his one bad inning after what looked like a third strike was called a ball and then two runs later came in. But hardly anyone mentioned the potential inning-ending double play ball hit right at Julio Lugo two batters later that Lugo let skip over his glove and into centerfield.

Naturally, it was scored a hit.

After watching Alex Gonzalez run halfway to the wall out in left centerfield to chase down a flyball with a sliding grab last week, you have to wonder what the Red Sox pitchers’ ERAs would be if the Sox had somehow had the vision to pony up a measily $4 million to re-sign the shortstop who should have been the AL gold glover last season.

Last time I checked, Gonzalez was outhitting Lugo this season as well.