Joe Philbin will be under pressure to get the Dolphins to the postseason in 2015. (USATSI)

Joe Philbin knows that his Dolphins have been consistently mediocre since he took over as the team's head coach. In Philbin's three seasons leading the Dolphins, he's accumulated a 23-25 record. And now, after spending big bucks on Ndamukong Suh, the Dolphins are entering the 2015 season with playoff aspirations, which means that another 8-8 finish for Philbin might not be tolerated by the organization.

On Sunday, Philbin made it clear that he knows .500 isn't good enough any longer.

"I came here to win championships. I didn't come here to be average and be 8-8," Philbin told ESPN.com. "(Owner) Steve Ross doesn't own the team to be average. Our fans don't want to be average. Our players don't want to be average. So that's what we're here for. That's why we invest and put the effort, the time into what we do."

The way Philbin sees it, there's more than just the Super Bowl available to win this season.

"There's three championships right now that are out there: There's the AFC East, there's the AFC and there's the NFL championship," Philbin said. "So nothing's been decided. I can honestly tell you sitting here we've had a couple of clunkers in three years. But we haven't had a ton of clunkers where we just got manhandled from start to finish. So I've gone into every game thinking we're going to win every game."

In stretches last season, the Dolphins did look like a playoff caliber team. But after a 7-5 start, the wheels fell off. The Dolphins finished the season by losing three of their last four games, dropping out of playoff contention in the process.

But expectations are still heightened for 2015. Quarterback Ryan Tannehill is coming off a season that saw him post career-bests in completion percentage (66.4 percent), yards (4,045), yards per attempt (6.9), touchdowns (27), and quarterback rating (92.8). And now, with the addition of Suh, a Dolphins defense that finished 12th in total defense last season will get a huge boost moving forward.

Combine those factors with Tom Brady's current four-game suspension, and the Dolphins have to be thinking about challenging for the top spot in the AFC East. But given the Patriots' dominance, it's tough to see the Dolphins overcoming them. And if that's the case, there's a chance the Dolphins will be looking for a new head coach come January.