This week, we’re wondering what’s wrong with Mike Wallace. The broad numbers aren’t bad — Wallace ranks sixth in the league with 939 receiving yards to go with 55 catches and six touchdowns — but he’s cooled off completely after a hot start, and his statistics have declined rapidly in recent weeks.

Wallace’s receiving yardage numbers have dropped in four consecutive weeks, from 118 to 70 to 68 to 54 to 17 this past week against Kansas City. That two-catch, 17-yard, zero-touchdown performance was his worst single-game output in two years.

Now, Ben Roethlisberger was dealing with a fractured thumb Sunday night, and that might have played a role. Big Ben averaged a season-low 6.2 yards per attempt against the Chiefs. But he still completed three passes of 20-plus yards, and none of them were to Wallace. His two longest completions of the night were to Antonio Brown, who has seemingly emerged as Roethlisberger’s preferred target.

Check out the last four games:

Brown: 23 catches, 343 yards, 1 touchdown
Wallace: 19 catches, 209 yards, 1 touchdown

That Wallace is now on pace to only barely surpass his yardage totals from 2010 is disappointing. That he’s still not even halfway to his lofty preseason goal of 2,000 yards is surprising, especially considering that Hines Ward has disappeared in 2011.

Roethlisberger’s thumb isn’t helping, and the wind in Cincinnati in Week 10 was not favorable for a deep threat like Wallace. Still, a season that started out with so much promise is going downhill fast.

Then again, as long as the Steelers are winning, Wallace might not care.