Hector Rondon registered a tremendous campaign for the Chicago Cubs in 2015. The closer finished 6-4 with a 1.67 ERA, 1.00 WHIP, 30 saves and 69 strikeouts in 72 games (70 innings), but his spring training performance is one concern too many.

In just four appearances (3⅔ innings), the 28-year-old has allowed nine earned runs on 13 hits and a walk, which has resulted in a 22.09 ERA, 3.82 WHIP and a .591 opponents' batting average. Wednesday provided the most troubling outing: he lasted just ⅔ of an inning and allowed five runs on seven hits.

His performances have gotten progressively worse as the Cubs approach Opening Day, and with an already questionable bullpen, Rondon's glaring struggles cannot be overlooked.

 "As long as he's healthy, that's all I'm concerned about," manager Joe Maddon said Thursday. "I really mean that."

At the end of the day, it is spring training and a lot of times there's not much to worry about when a player isn't a sharp as they're expected to be, but Rondon started off with just one earned run on three hits in his first two innings and that since has snowballed into eight earned runs on 10 hits in 1⅔ innings.

His health could be a factor, but at this point Rondon says he feels healthy and the team hasn't had a reason to explore that just yet.

There's obviously no steady pattern of Rondon struggling yet being that he's really only had two bad outings, but the concerns will mount if he ends spring training on this note. The weakest aspect of the Cubs' MLB roster is their bullpen and they can't afford to have Rondon limping into 2016 with no confidence after a horrid spring training.

Rondon is pleased with his improving velocity as well as the location of his pitches. He said he doesn't want to give up runs in his next three or four outings, but he said it would be "no big deal" if the opposition were to score runs if his pitches and location were good.

Still, it'd be nice if the Cubs didn't have to worry about the right-hander, considering their bullpen situation isn't exactly what you would call fluid. With Rondon, Travis Wood, Pedro Strop, Trevor Cahill, Justin Grimm, Clayton Richard and Adam Warren, the unit is far from elite and the club cannot afford significant lapses from that area of the roster.

Maddon managed the bullpen tremendously last season when he began using a closer by committee system with Rondon, Strop and Jason Motte, but it's safe to say he doesn't want to have to deal with constantly mixing and matching relievers during a year when the Cubs are the favorites to win the World Series.

Rondon has plenty of time to recover, but it's worth noting the team will need to keep a close eye on him from this point forward.