Miami Dolphins running back Jay Ajayi has struggled to prove his worth this preseason. A hamstring injury limited him early during Dolphins training camp, and it wasn't until Thursday night, in Miami's final preseason bout against the Tampa Bay Buccaneers, that he began to display the talent that got him drafted in the fifth-round of the 2015 NFL Draft. Unfortunately for Ajayi and for Dolphins fans, the bruising running back's night was brought to an unexpected close after he suffered what, per Adam H. Beasley of the Miami Herald, turned out to be a broken rib.

Ajayi told reporters after the game that he wasn't "overly concerned" with what was initially deemed a chest injury, but with the news that it was, in fact, a cracked rib, the outlook for his rookie season has likely changed drastically, though Andrew Abramson of The Palm Beach Post is reporting that the team is liking to keep him on the active roster for the season.

Ajayi, viewed by many as one of the more talented tailbacks available in April, tumbled down draft boards due to questions over his health - and specifically his knee - and his physical running style. While the hamstring injury he dealt with early in training camp was likely due more to a lack of conditioning, the combination of his questionable knee, the hamstring and now the rib may be cause for long-term concern over Ajayi's ability to stay healthy.

Ajayi was playing well at the time of the injury, having carried the ball nine times for 66 yards. He had also caught two passes that went for 37 yards. Dolphins head coach Joe Philbin seemed happy with the performance, noting that Ajayi had "made a guy or two miss" and "showed toughness inside."

The top of the Dolphins running back depth chart remains set with Lamar Miller tasked with carrying the load and Damien Williams and LaMichael James adding an extra punch.

Still, the rib injury is certainly a setback for Ajayi and potentially a clear indication that perhaps the Dolphins should have steered clear of him on draft night.