Countdown to Opening Day - 24: Tigers' bullpen needs Joe Nathan of old

In this 30-day series, theScore's MLB editors will preview the 2015 season with an in-depth look at some of the significant numbers - statistical milestones, jersey numbers and general miscellanea - poised to pop up throughout the campaign.

Joe Nathan's first year with the Detroit Tigers was full of ups and downs, and now, at age 40, the right-hander is only 24 saves shy of 400 for his career.

Nathan will likely join Mariano Rivera, Trevor Hoffman, Lee Smith, John Franco and Billy Wagner as the only closers to record 400 or more saves, if he can remain healthy. What's even more impressive is the number of saves Nathan has recorded in only 14 years compared to some of the greatest high-leverage arms of all time.

The problem? Nathan is coming off one of his worst seasons statistically as a reliever. He blew a career-high seven saves in 2014, while recording an ugly 4.81 ERA and 1.53 WHIP in 62 appearances. Nathan's 1.86 strikeout-to-walk ratio was also the lowest of his career. But he still earned 35 saves, which ranked 13th in the bigs.

Nathan's frustrations boiled over Aug. 13, when he flipped off the home fans, who were frequently booing him throughout the dog days of summer - and really let him hear it after walking the first two batters he faced against the Pittsburgh Pirates.

"I learned a ton about myself as a human being," Nathan said after issuing an apology for the gesture. "I think I'll be better for that, I'll be stronger for that. I'll be able to deal with tougher situations."

The Tigers' bullpen struggles have been blamed for the team's failure to bring a World Series championship to the Motor City, despite four consecutive American League Central titles. Detroit relievers combined for a 4.29 ERA (27th in the majors) and allowed opponents to hit .270 (29th) in 447 innings of work.

President and general manager Dave Dombrowski hasn't added pieces to improve the bullpen this offseason, and is hoping his current relief corps can bounce back, including Nathan.

"I don't want people to think I'm done," Nathan said at the team's Winter Caravan event in January. "I think coming into not just the spring, but coming into the season, I want to prove to myself and other people I still have something left in the tank."

Nathan altered his offseason workout routine, opting for an agility-based program, which he says has him feeling stronger than ever. 

Good luck, Joe. We'll be watching.