Cardinals All-Star reliever Pat Neshek has a spot in his heart for the A’s, calling his time in Oakland in 2012 and 2013 “the most fun time I ever had playing baseball.”

From afar, he saw this year’s A’s fade down the stretch and lose their wild-card game to Kansas City.

“Just for me,” Neshek said, “I feel if he had just left that team alone from June, I think they’d still be playing now. That’s just my personal opinion.”

General manager Billy Beane made several significant second-half moves, and his Yoenis Cespedes-for-Jon Lester trade has been dissected every possible way and either applauded or ridiculed depending on the source.

“I see where he’s at,” Neshek said. “We got beat with the lack of starting pitching depth. (Detroit’s Justin) Verlander kind of shoved it against us (in the playoffs) those two years. I could see why he wanted to do those moves, but I felt that team was just starting to grow. Now I feel they kind of hurt the minor-league system a little bit.”

Neshek said he noticed the A’s weren’t as threatening without Cespedes.

“I don’t know what it was, but I definitely know that had to be a chemistry issue,” he said. “Cespedes, he kind of struck a lot of fear into opposing teams. We all watched that, especially in the two years I was there. You take him out, it makes a lot of the other guys a lot less scarier in the lineup.”

Neshek added . . .

“For me, the chemistry we had there in ’12 and ’13 was just incredible. I haven’t been there (this year), but standing away and looking at it, I feel that kind of got hurt a little bit there. That was the best group of guys. They were young, hungry.

“You knew a lot of the guys were going to be star players down the road, but I think the team chemistry was definitely hurt when they started adding those guys, taking (Jesse) Chavez out of the rotation; he probably would have been fine the whole year.

“That’s kind of how I felt last year. I was told at the end just go home. I feel when you do little stuff like that, it affects the club.”

Asked to elaborate, Neshek said, “At the end of the season last year, I was on the plane and they said, ‘We don’t need you for the playoffs, and we don’t need you to stick around, either.’ Here (in St. Louis), we have 35 guys still here, 10 of them aren’t even on the roster. But they’re here, and they travel.

“This is my sixth playoff team, and I got to travel (in years he didn’t make the playoff roster). I felt like part of the team. That goes a long way.”

Neshek had a 1.37 ERA in 24 games with the 2012 A’s. Last year, it was 3.35 in 45 games – as low as 2.34 before a couple of rough outings in August. He had hoped to make a bigger impact.

“It was fun to be around those guys. It was a fun clubhouse,” Neshek said. “But personally, I felt I could do so much more. I’m not one to speak up and go in the manager’s office or go talk to the GM and say what can I do to get better. It speaks with the innings you get out there. I just feel I could’ve done a lot more.”

Neshek signed a minor-league deal with the Cardinals on Feb. 6. He earned a spot on the Opening Day roster and was picked as an All-Star, thanks to his 0.70 ERA at the break.

“It was nice just to get that opportunity,” Neshek said of joining the Cardinals.

His ERA in 71 games was 1.87, and he appeared in all four Division Series games.

“Pat has been one of those huge surprises,” Cardinals manager Mike Matheny said. “We walked into spring training thinking we were going to have a right-handed version of Randy Choate (like Neshek, a sidearm pitcher) and not even know if he’s going to make our team to a guy who can throw the seventh, eighth and ninth.”