It seemed like a safe enough assumption; Jake Fox had made 10 starts in left field this season and he’d hit .286/.332/.526 in his 175 at-bats for the Cubs. Of course he was going to see additional playing time with Alfonso Soriano being shut down with a knee injury. It was a given. But now it’s Sept. 11, and Fox was on the bench for the seventh straight game Friday against the Reds. He hasn’t started since going 2-for-4 with the Cubs’ only extra-base hit in a 5-0 loss to the White Sox on Sept. 3. Soriano has missed all seven games since. Milton Bradley just missed one Wednesday. Derrek Lee and Aramis Ramirez have each had a day off in the span. Yet Fox has been limited to three pinch-hitting appearances. The most stunning absence came the very day after the shutout. Fox hit a grand slam off the Mets’ Bobby Parnell on Aug. 29, yet didn’t start when Parnell faced the Cubs again on Sept. 4. The Mets ended up winning that game 6-2 behind seven scoreless innings from the rookie. The whole scenario seemingly has Cubs writer Carrie Muskat baffled. “Fox has opportunity to step up for Cubs” was the headline for her preview column for Friday’s game. That was written after Fox had sat out six straight. I’m pretty baffled myself, but it’s clear Fox is in manager Lou Piniella’s doghouse. He has yet to prove adequate anywhere in the field, whether it has been his 22 starts at third, his 12 in the outfield or his two at first base. The former catcher has also been behind the plate for seven innings, but the Cubs saw so little to like there that they had Koyie Hill catch every single game when Geovany Soto was forced to the DL for a month. It’s still hard to justify the current treatment, though. When given the chance, Fox has provided oodles of power to a lineup that’s been surprisingly short of punch this season. Maybe he shouldn’t be a full-timer given his limitations, but about the only time he definitely shouldn’t play is when flyball pitcher Ted Lilly is on the mound.