In spite of a 4-1 win last night against the Pirates and a 2-1 series win, the Cubs offense continues to struggle - they scored seven runs in three games against Pittsburgh and managed to get shut out by Russ Ohlendorf. It’s time to examine some of the culprits.

One of the better ways to do this is through Weighted On Base Average. If you don’t know wOBA, you can check out that link for an explanation. But in short, it attempts to assign a value in runs to everything a player does at the plate, and then gives you an average of that number per plate appearance. The whole thing is then multiplied by a coefficient so that the stat works on about the same scale as on-base percentage.

So here’s a table of the wOBAs of all Cubs hitters with 100 PA or more. I’ve included, in red, the 2008 national league average, and a rough estimate of what “replacement level” is. The idea behind replacement level is that any given team probably has a player who can perform at about this level just hanging out at AAA - basically that’s about level of production you would expect in the long term from a career minor-leaguer. A team full of replacement-level players would be historically bad.

Not a lot of surprises at the top or the bottom. Derrek Lee has been the best regular for the team this season, having completely made up for his slow start and then some. Aaron Miles has been positively awful. Fukudome has fallen off as the year has gone on, but his cumulative numbers are still solid. Reed Johnson has been very good, although he’s on the disabled list right now. Theriot has been about average - which isn’t actually bad at all for a shortstop, who are often below average.

It’s sort of surprising to see that Bradley is right around average, but he’s getting on base well — at a .355 rate before his two walks last night. The Cubs expected more than that out of Bradley, and you don’t want a corner outfielder to be just average at the plate, but there are bigger fish to fry.

Soriano and Fontenot are the most disturbing names on that list. Soriano has completely wiped out what was a very hot start and is playing very badly. I don’t know if it’s all attributable to his knee or some of it’s just a funk he’s in. Lou rested him last night and I sort of hope he rests him tonight as well. Ideally, I think, when Ramirez comes back on Monday, Soriano should be disabled until the All-Star break, if he just needs to get healthy. If that’s not it, he just has to ride it out and hope he improves, but I don’t think it is.

Meanwhile, Fontenot has been a problem too. He hasn’t been very good against righties, but he’s been terrible against lefties, going just 5-36 with only two extra-base hits. He got a little exposed by the Ramirez injury — while the team hoped he was going to be an every-day player, it doesn’t look like he is now. But having been forced into the role of every-day third baseman, he both had to deal with playing out of position and with having to face more lefties than he might otherwise. If the Cubs can protect him by using him less, and in position, he still has some value, but they need to keep him from playing against left-handed pitchers.

And the best news here is that on Monday, with Ramirez’s return, everyone should benefit. Miles has more or less lost his role on the team already, and Fontenot will be pushed back into a role that suits him better. Meanwhile, a tough out is added to the lineup which can’t hurt Bradley and Lee in terms of the pitches they’re seeing. It also frees up Jake Fox to potentially platoon a little in the outfield with Micah Hoffpauir and give Soriano and Bradley a little more rest or time to work on their swings. Even if Ramirez himself isn’t topping this list in a month, I expect more players to be above average and above replacement than there are now.