Running back Arian Foster didn’t sign with the Dolphins until just before the start of training camp, but he didn’t need an entire offseason with the team to head into the regular season as their starting running back. Foster has been installed as the No. 1 back on the depth chart, something that may have come as a surprise to some people because he’s coming off a torn Achilles and turned 30 this year. Foster doesn’t see anything that remarkable about his return to the top of a depth chart, however. “I wasn’t dead,” Foster said, via ESPN.com. “I had an injury. I’ve bounced back before. … You hear all the geniuses say that is what’s supposed to happen at 30. I feel like if you take care of your body and you train like I train, you should be able to do good things.” Foster did bounce back from missing half the 2013 season to turn in 1,246 yards and 13 total touchdowns for the Texas in 2014. Those totals would make for a lot of smiles in Miami and provide balance to the offense that’s been missing in Miami in recent seasons.Better offensive line play would help in that regard and the Dolphins hope starting Laremy Tunsil and Jermon Bushrod at guard will provide it, although it’s unclear when center Mike Pouncey will be ready to go because of a hip injury.