The question is simple. But for Mike Zunino, the answer isn’t. “What’s it like to catch Felix Hernandez?”

Zunino pauses and thinks about it.

“It can be difficult,” Zunino said. “It’s hard. But I love doing it.”

For all the reasons the Mariners’ ace is tough to hit, he’s difficult to catch. Sure, Zunino knows what’s coming, but that doesn’t mean every pitch will do the same thing.

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“You can’t put into words and can’t describe it to someone who maybe hasn’t played the game or even someone who has played, just how much his pitches really move,” Zunino said.

Hernandez’s four-seam fastball — the most simple of pitches — is anything but straight.

“I’m not fabricating when I say it moves four to five inches every time,” Zunino said. “It’s got natural life.”

It’s not just the fastball. It’s all of the pitches.

“Everything is so explosive, with late movement,” Zunino said. “You have to be on your toes.”

Many a Mariners catcher has been overwhelmed by Hernandez’s volatile stuff.

Zunino, who has caught every Hernandez start this season and six starts last season, said he believes repetition makes it easier.

“It takes time,” he said. “Once you get an idea of what he likes to do and what his stuff does, then it becomes easier. You learn what he likes to do and anticipate what the ball is going to do.”

Zunino’s favorite pitch is Hernandez’s changeup. There are two variations — one for a strike and a two-strike wipeout pitch that’s almost always in the dirt.

“Devastating is the only word,” Zunino said. “You see guys that think they are right on it and they miss it by a foot. I forget who it was, he swung through it two times in a row and said, ‘I can’t tell. Is that a split or a changeup?’ I looked at him, ‘I don’t even know.’ ”

It’s that good.

“I think it’s the only pitch in baseball that a hitter can sit on and still not square it up,” Zunino said.

The reactions to Hernandez’s pitches are priceless.

“When he has it going, you can sense the frustration as the game goes on,” Zunino said. “They are on their second and third at-bats and having the same results. You can just sense the frustration, whether it’s a mumble or they take extra practice swings and you see it on their face. It’s fun to see how frustrated he can make hitters.”