Left field is another easy place to predict what’s going to happen in 2010 - Alfonso Soriano will be the starter. He makes too much money and has too long of a track record of success to bench him or trade him. He’ll bat fifth or sixth, as Lou PIniella declared that the days of Soriano batting leadoff are over.

The big question with Soriano is what will his health be like next season? He’s getting older and we can expect his performance to decline, but he fell off a cliff after a hot April this year. Not coincidentally, his performance nose-dived after he hurt his knee. He had surgery on the knee a week ago, and his doctor found inflammation and cartilage degeneration. The good news is that coming back from the knee surgery should be easy enough. The question going forward is whether Soriano can stay healthy aside from that.

The good news there is that Soriano has generally been good even when he hasn’t been 100 percent, this injury aside. He was very good in his first two years as a Cub in spite of a couple of injuries which lingered a bit. The bad news is that as he keeps getting older, he’s going to keep getting hurt and have more trouble recovering from injuries.

More than anything else, Soriano’s injury seems to have deprived him of his power. He hit .241/.303/.423 this season, with 20 home runs in 522 plate appearances. He only hit home runs on 11.5 percent of his fly balls, down from around 16 percent or 17 percent in his first two seasons as a Cubs and down from 15.3 percent on his career. If we assume that the decline is due mostly to the knee injury, and not to age — because it’s odd that he would have started showing his age suddenly after having a great April — we can guess what he might have done had he not gotten hurt. (All stats via FanGraphs.)

Soriano hit 174 fly balls this season, 20 of which went for home runs. If he had hit according to his career average, 15.3 percent of them, or 27 (well, 26.6, but we’ll round) would have been home runs. Assuming nothing else at all changed his season line then would have been .256/.314/.482. That’s an OPS of .796. It would have still been a down year for Soriano, but not nearly as disastrous. The odds are that if he had had a little more power he would have walked a little more, too. And without a bum knee his defense, which was also down this year, would have been a little better. He may not have been able to carry the team, but he probably wouldn’t have been the drag on it that he was this season.

So, I’d expect Soriano to rebound some next year. He’s getting older and he’s probably going to continue to decline, but with his knee healthy he should be good until the next injury. If it’s the sort of injury that saps power and speed, again, he could be in for another disastrous season. But if he can stay reasonably healthy he’ll be a positive contributor, even if not quite worth what he’s paid.