Mission accomplished for 49ers' Troy Smith

Ted Marchibroda isn't coaching the San Francisco 49ers. The team might be heeding one of the former NFL coach's axioms about backup quarterbacks, however.

As Marchibroda likes to say, a good backup quarterback might be apt to win three games in relief, but if a team leans on him for six games, he'll likely lose three as well.

The 49ers have gone 3-2 with former third-stringer Troy Smith at quarterback. They've lost two of his last three starts, however, and with the 49ers' season on the line Sunday, the team is giving the job back to former starter Alex Smith.

Troy Smith has accomplished what a team should expect its backup quarterback to accomplish. He sparked the team. He won a few games. But the longer a backup is on the field, the tougher his job becomes. Opponents become better prepared for what the backup offers. Over time, the backup quarterback often shows why he's a backup.

We can debate whether Alex is better than Troy, but there's no question Troy Smith's play has leveled off. That was expected. "Unsustainable" was the word I used to describe his initial numbers. He was averaging 17.9 yards per pass attempt on first down through his first two starts with the team.

The chart shows how Troy Smith's first-down passing numbers have plummeted. Taking away the threat of Frank Gore, lost to a season-ending hip injury, makes it even tougher for the 49ers to fool defenses on first down.

On a side note: The 49ers' inability to prevent word of their impending quarterback change from getting out before Wednesday gave the Seahawks two additional days to prepare for Alex Smith. Perhaps Pete Carroll should thank Mike Singletary for the heads-up. That seems only fair after Singletary thanked Carroll following the Seahawks' 31-6 victory over San Francisco in Week 1.

Troy Smith's first-down efficiency