Rankings Dolphins' biggest offseason needs: No. 3

The Miami Dolphins are coming off back-to-back 8-8 seasons and enter a playoff-or-bust year in 2015. In order to accomplish that goal, they must fill several key needs.

ESPN.com's Dolphins page continues its rankings of Miami's top-5 needs.

No. 3: Guard

2014 starters: Mike Pouncey, Daryn Colledge

Top free agents: Mike Iupati, Rob Sims, Clint Boling

Why it's an issue: The Dolphins don't just need one guard. They need two new guards entering the 2015 season. Colledge, 33, is a free agent who is unlikely to return. Meanwhile, Pouncey will move back to center next season, which is his natural and best position. Miami must do all it can to protect starting quarterback Ryan Tannehill, who has been sacked 139 times in three seasons. Getting stronger up the middle is one way.

Walker's solution: The Dolphins should not spend top dollar in free agency on a guard. Yes, it's a big hole, especially with two positions to fill. However, Miami must coach up its young offensive linemen to step up. The Dolphins spent a pair of third-round picks on Billy Turner and Dallas Thomas in 2013 and 2012, respectively. Thomas got a brief look at the end of the season with two starts but struggled and wasn't ready. If either prospect is worth their salt and the coaching staff does its part, at least one of these players should be ready to fill a hole in 2015. Turner has the most potential of the two with good size and a physical mentality. It also wouldn't be a bad idea to take a guard in the second round or lower.