It certainly wasn't David Garrard's on-field performance that got him cut Tuesday from the Miami Dolphins.

The reason Miami let go of its best quarterback in spring practices and training camp was his lack of durability. It's that simple.

The Dolphins couldn't trust the 34-year-old quarterback to stay healthy. He missed all of 2011 with a back injury and tweaked his knee while playing with his children at home. That knee tweak required surgery.

If Garrard needed surgery from playing while taking it easy at home, imagine him taking hits from 300-pound defensive linemen. That had to weigh into Miami's thinking.

As a result, the Dolphins chose Matt Moore as the backup to rookie quarterback Ryan Tannehill. Moore was not the better fit for Miami's offense. But Moore is younger and without injury concerns. Health matters in the NFL, and in this case, more than performance.

If health and age hadn't caught up to Garrard, he probably would be Miami's starting quarterback Sunday against the Houston Texans. But age catches up to everyone in the NFL. Garrard was the latest victim.

Cutting Garrard also means Miami probably will stop fielding offers for Moore. The veteran quarterback, who went 6-3 in his final nine starts last season, had some trade value. Perhaps the Dolphins could've gotten a wide receiver or a future draft pick for Moore.

But Tannehill, Moore and a developing Pat Devlin aren't a bad trio of quarterbacks to take into the season. This is one of the few areas of depth on Miami's 2012 roster.