Miami is different than most other teams when it comes to the o-line. In recent history, with few exceptions, Miami's best o-linemen have been players drafted by other teams, and most of them were merely average at best, with just the occasional decent starter. Also, it doesn't help when your starting Free Agent LT and LG are both injury-prone. I'm sure that there will be guys cut from other teams, whether due to salary cap issues, or veterans with a year or two left replaced by someone younger, that would be an upgrade for Miami.
Ever since Philbin, Miami has spent money and/or draft picks for Free Agent o-linemen, and to this day still have o-line issues. It's a real shame that Miami's Front Office is clueless when it comes to building a competent o-line through the draft, and just using Free Agents to fill a hole or as experienced back-ups.