The Detroit Tigers thought Joe Nathan could be coming off the disabled list this week, but instead the closer suffered a season-ending injury in his rehab assignment. What could be their next plan of action?

Nathan was set to earn $10 million this season and has a $10 million team option or a $1 million buyout for 2015. They now need a significant upgrade at the back end of their bullpen to add both depth and a sure-fire option to close games especially since the club has struggled in that department over the past few seasons.

"Joe Nathan is out for the year, and the Tigers' bullpen is worse for this development," writes ESPN's Buster Olney. "Evaluators with other teams said privately Thursday that they thought that in the big picture, from a purely practical standpoint, this is a fortunate development for Detroit, assuming that the Tigers have insurance on Nathan's contract; they can flip that money and upgrade the team in other ways."

Could that upgrade be Philadelphia Phillies closer Jonathan Papelbon?

The veteran is owed $13 million this season and has a $13 million vesting option for 2016 that kicks in if he finishes 48 games this year. If Detroit had Nathan's contract insured - considering they were aware he previously underwent Tommy John surgery - they could probably make it work with Papelbon's remaining money.

The Phillies' closer spoke with Jim Salisbury of CSN Philly about his situation in Philadelphia and his comments could foreshadow such a move in the near future.

When asked if he would be upset if he's not dealt at some point this season, the right-hander responded:

"Yeah, I will be. If we continue to lose.

"If we can rebuild this situation and make it right, and we can get some wins underneath our belt and Ryne Sandberg can get us going, that's a whole different story."

However, it's highly unlikely the Phillies will turn it around. They're expected to be one of the worst teams in baseball this season, if not the worst, because of their current rebuilding situation and declining play of their veterans. Soon enough, general manager Ruben Amaro will come to his senses and realize he needs to get value for his expensive veterans, particularly Papelbon and Cole Hamels.

Papelbon could be the next to go being that a few clubs are having issues with their bullpens.