With Marquis Daniels injured, Von Wafer stands alone as the Celtics’ only backup small forward. There’s just one problem: Doc Rivers doesn’t think Wafer can handle the role.

“He’s not big enough to be that guy,” Rivers told WEEI, later adding, “When Paul goes out, somebody’s going to have to guard LeBron. We don’t have that someone.”

Looking at Wafer’s stats — not to mention his thin, 6’5″ frame — Rivers has a point. Wafer hasn’t played much small forward this year, but did play a fair amount in ’08-’09 with the Houston Rockets. During his time at small forward that season, according to 82games.com, Wafer surrendered a PER of 19.5 to his opponents (well above the league average PER, 15). Compare that number to 14.9, the PER Wafer’s opponents registered when he played shooting guard that season. Wafer clearly had more trouble defending larger players.

There is another side to the story, though. Wafer actually played much better offensively when playing small forward. His own PER rose from 14.3 as a shooting guard to 19.7 as a small forward, meaning Wafer’s Net 48-Minute Production improved when he moved to small forward. Of the three most common lineups featuring Wafer at small forward that season for the 53-29 Rockets, each outscored its opponent.

Of course, Wafer’s role is different now. He’s unlikely to provide scoring binges like he did for Houston that year, because the shot attempts just won’t be there. In Boston, Wafer has to carve his niche with strong defense and solid, rather than spectacular, offensive play. Wafer’s new role in Boston could make his inability to defend small forwards more troublesome, as his offense is less likely to make up for his defensive deficiencies.

Given that he doesn’t feel Wafer can handle the league’s larger small forwards, Rivers has already begun to make defensive adjustments.

“We’re going to have to do something,” Rivers told WEEI. “We worked on it today and I’ve been here seven years and you’ve seen me trap probably 10 times. We’re going to have to start trapping, which weakens your defense. I hate it. But we worked on it today and we’re going to work on it every day until we get another [small forward].”

One effect of Marquis Daniels’ injury is already rearing its ugly head. The Celtics are changing their entire defensive strategy because they don’t think Wafer can adequately fill Daniels’ role.