Count Didi Gregorius among those who think MLB’s playoff expansion idea should be thrown in the Astros’ garbage can.

The former Yankees and new Phillies shortstop has been to the postseason the past three years and believes the current system is just fine. The idea of nearly half of MLB making the playoffs — seven teams from each league — may not incentivize teams to spend as much, he said.

“It’s supposed to be the best teams go, right?” Gregorius told The Post recently in Clearwater, Fla. “So now you have a team that doesn’t pay the top guys a lot of money, but now they get a chance to go. They didn’t even play hard, maybe win 80 games or 70 games, but now you’re in the playoff run. It’s not like you’re fighting to be in the top. You’re just walking in, it doesn’t matter how I play, because we’re going to walk in anyway to the playoffs.

“It’s not football or any other sport. This is the only sport we play 162 games. It’s not like you’re playing 16 games or eight games a year. It’s a huge difference. That’s the reason you gotta keep fighting because now you just have people walk in because you don’t have to compete. It doesn’t make any sense.”

Gregorius also had a problem with the prospect of the top seed having too long of a layoff. As The Post’s Joel Sherman reported last week, the new playoff proposal would give the team with the best record in each league a bye into the Division Series. The other six teams in each league would then play each other in a best-of-three wild-card round.

“It’s not fair. It’s not fair for the first seed because now you have to sit 10 days or however many days,” Gregorius said. “Now your best starter’s not going to be ready. It’s a pick-and-choose. Just let it be the way that it is.”

Currently, the top seed plays the final game of the regular season on Sunday and begins the Division Series either Thursday or Friday. Under the proposed format, that schedule might only have to be pushed back a day — so not quite as long as Gregorius believed.

Still, Gregorius said if MLB’s end goal was getting more fans involved, he has better ideas on how to accomplish that.

“If you want to make changes to get kids involved, lower the prices,” he said. “Get more stuff, [get rid of] the blackout restrictions. If you want to get kids involved, that’s how you get them involved. Guys have shoe deals that they can actually make shoes so kids can buy them at the field or do something different. That’s the type of change you want to do because that’s where you want the kids to be involved. So you should do more stuff for the kids.

“If you’re a dad with three kids and you pay 200 bucks because you want to go to one game — or $250, however much the tickets are. So it’s just the difference of getting to afford it. Because now you buy food for all of them. By the time you leave, it’s like 300 bucks. Not everybody has that type of money to spend every day to go to a baseball game. If they can watch it at home and without the blackout restrictions and all that stuff, they get to enjoy it more.”