This has not been a good preseason for the Miami Dolphins.

Versatile offensive lineman Nate Garner was put on injured reserve with a broken foot, and will be out for the season. He joins defensive end Philip Merling, who tore his Achilles' tendon, as players who won't help Miami in 2010.

Starting linebacker Channing Crowder missed the last preseason game with a mysterious abdominal injury, which has yet to be diagnosed.

Cornerback Will Allen's recovery from knee surgery has been slow, and he likely won't play again until the start of the regular season.

Secondary play has been shaky this preseason, as it was last year, when the Dolphins ranked 28th against the pass.

Sean Smith, who was the team's best cover corner as a rookie, has struggled, as he's been beaten regularly in each game so far, and he's been benched three separate times. Vontae Davis has shown improvement, but he too has been inconsistent in game action.

Rookies Jared Odrick and Koa Misi, who were supposed to add playmaking ability to the defense, have largely been no-shows in preseason. Odrick has done little besides recover a fumble against Tampa Bay, and Misi has been missing in action, failing to generate much pressure from his outside linebacker position.

In fact, due to his inability to hold the corner on run plays, Misi has been replaced on the first team by Ikaika Alama-Francis, while he works at another position -- not a good sign of his progress.

The offense has been a mystery: Explosive against Jacksonville, and horrendous against Tampa Bay and Atlanta.

One thing that is certain is the running game has been nonexistent so far, exemplified by the fact the Dolphins' first unit gaining just 10 yards on nine rushing plays last week against the Falcons.

The receivers have dropped too many passes, led by new acquisition Brandon Marshall, and Chad Henne has been erratic so far.

Again, it's only preseason, but the coaches are worried after the loss to Atlanta, and with just one dress rehearsal left before the season starts next Thursday, you have to wonder if these small problems will add up to bigger ones as the season begins.