The bullpen is the most volatile part of a ballclub. With the exception of elite closers and specialists, relievers tend to be erratic with a good season followed by a shaky year. File Ken Giles in the latter group. The righthanded flamethrower is following up his exceptional rookie season with an outstanding spring.

Giles, 24, has posted a 1.59 ERA with a 1.24 WHIP so far in Grapefruit League action. “He has the makings of someone that is really special,” a NL scout said.

“He looks great down here. When you look at the Phillies and the future, you have Giles, (J.P.) Crawford, (Maikel) Franco and (Odubel) Herrera. The difference between Giles and those guys is that he’s not just going to be potentially doing it in the future. He’s doing it now as well.”

The Phillies wouldn’t mind dealing Jonathan Papelbon. If the Phillies can trade the expensive, experienced closer, the job would land in Giles lap.

“I’m not thinking about that,” Giles said. “I just think about going out there and getting outs. It doesn’t matter what inning it is. I just have to do my job.”

Giles does just that in a cool and efficient manner. What’s as impressive as his 100 mph fastball is how unflappable he is on the mound. After giving up a homer to the first batter he faced in the majors last season, a fly by then Padre Yasmani Grandal, which barely cleared the left field wall at Citizens Bank Park, Giles shrugged it off and finished off the next three batters.

“I remember that well,” Giles said. “I kind of laughed about it. The first hitter I face as a major leaguer homers off me. Oh well. I just thought, “I’m going to get the next guy and as many guys as I can after that.”

Giles was a revelation in 2014. He finished with a 1.18 ERA and a microscopic 0.788 WHIP.

“It was a really good season for me but that was then,” Giles said. “This is a new season. There are new challenges. I can’t dwell on the past. I can only deal with the present.”

The  Albuquerque native has no problem looking back. At this time last year, Giles had location issues and there were questions about his slider. 

“I remember the things that I had to work on last March,” Giles said. “I went back to the minors and worked on them.”

Giles arrived in the majors last June with impressive command and a slider, which is absolutely devastating. Giles is reminiscent of a young Brad Lidge, who possessed a blazing fastball and an unhittable slider as an Astro a decade ago. “That’s high praise,” Giles said. “But the thing is that I know I still have stuff to work on. I just want to keep getting better and better.”

That’s bad news for major league hitters.