Ryan Dempster pitched for 16 years in Major League Baseball. He is the co-host of MLB Network’s “Intentional Talk.” These are the three best leaders he played with in his career.

Greg Maddux, Chicago Cubs pitcher

In my first year with the Cubs in 2004, we lost the second-to-last game of the season and were eliminated from the playoffs. Greg was supposed to start the next day, and I remember our manager, Dusty Baker, coming down to him in the locker room: “Do you still want to start tomorrow?”

Greg looked at him and said, “Damn right I do.”

I asked Greg later about what was so important about that last start. He told me, “To start the last day of the season is just as important as starting the first game of the season.”

That’s all he said, and I never asked him why he said that. I just thought about it a lot, and I think that summed him up.

He led by example better than anyone I’ve been around. I just watched him. I watched how he went about his business and prepared.

I learned a lot about routine from him. Greg understood the different ways the smallest edge could help you win a game. He was always looking for that edge like a master card player: If he found a tell, he would exploit it to his advantage like no other.

It’s funny because I was a weight-room guru. I loved being in there, I loved working out. That wasn’t necessarily Greg’s strong point. But every single day at 6 a.m. in spring training, he’d be on the Precor machine getting his cardio in.

I learned a lot about accountability. I saw him do things that I’d never seen before. I watched him walk into the training room after giving up three runs in the first inning and tell our team doctor where to stick the Marcaine or novocaine or whatever he had shot in his arm to numb it.

Think about that. He walked into the training room, pointed to his shoulder and said, “Right here, doc.” And then he went out and threw six shutout innings after giving up three runs in the first.

I was like, Who is this guy? I’m not going to ever complain again if I don’t feel that great.

I learned how to be a better teammate. A guy comes in after scoring a run, who was one of the first people there to give him a high five? Greg Maddux. Starting pitchers disappear all the time during games. But he was always in the dugout, except for the day before his start, and that’s only because he was inside charting pitches.

It made me go, Man, I could be a better teammate because of the way this guy is.

The numbers don’t lie. Look at my career ERA before playing with Maddux (5.01) and after playing with him (3.90). He helped me that much.

Mark DeRosa, Chicago Cubs infielder

He had the ability to connect a locker room.

It was as important to him to be connected to the superstar on the team as it was to be connected with the 25th guy on the roster. He wanted to make sure that everybody was pulling on the same rope.

He also had an innate ability to poke the guys who needed to be poked, to coddle the guys who needed to be coddled and to press the guys who needed a little more at their backs.

He held people accountable: “Hey, dude, run down to first base today. I don’t care if you go 0 for 4, I need you to run down to first base every time.” He was not afraid to have those uncomfortable conversations as a teammate, and that’s not easy.

There was a brief stretch in 2008 when we had a guy who just wasn’t very interested in taking batting practice on the field. We were kind of struggling. It was Aramis Ramirez, and Mark went up to him and said, “Hey Rammy, we need you out there. I need you there. I need you hitting in my group.”

Sure enough, Rammy was out there hitting.

Mark knew when to call for a team dinner, a card game or a group hang in a room. He could read what the team needed as well as anyone I ever played with. And if you look at those two years in Chicago, we won back-to-back division titles. Mark played a vital role in that.

We all get caught up in our roles. I’m a third baseman. I’m a second baseman. I’m a starting pitcher.

For him, it was: I just want to win. If that means I play right field, second base, shortstop, I don’t care. I believe I can be an everyday player at one of those positions, but I’m not here to complain about that.

When you’re around that, you start to put your team first instead of your individual goals. It’s contagious.

Dustin Pedroia, Boston Red Sox second baseman

No player in my big-league career was more prepared than Dustin Pedroia. I’m not going to say he was the most prepared because I don’t want to disrespect anybody who put everything they had into it, but there wasn’t a more prepared player.

He left nothing to chance.

You show up to the ballpark at noon, and he’s already taken 50 groundballs. You want to come early and hit? He’s already down at the batting cage.

When the best player on your team is setting the biggest example, it’s hard for everybody else not to fall in line.

I love David Ortiz, but he could be watching an episode of “Family Matters” between innings and then go out and hit a three-run home run. That was a different kind of confidence, and it wasn’t always necessarily what you wanted young guys to look to. They just saw the result; they didn’t see all the work David put into the cage.

With Dustin, you saw it. You saw the accountability. He left nothing to chance. He never took a pitch off.

This is an incredible Pedroia story. We were in New York to play the Yankees, and it was a 7:05 p.m. start.

Pedey was in full uniform at 6:05. He was in the locker room, eating his Little League pregame meal. I think it was a peanut butter and jelly sandwich or a ham and cheese sandwich with Doritos and an Orange Crush — total 12-year-old meal.

We were all wearing him out. It was myself, Clay Buchholz, Jon Lester, John Lackey and David Ross. We were like, “Bro, are we doing baseball card pictures today?”

He was sitting there, eating his sandwich, not paying attention to us.

So then we were like, “Oh, wait, wait, wait. I know. You and your wife are doing your Christmas cards today. Is that why you’re in your full uni?”

We were burying him. He didn’t say anything.

He finished his sandwich and chips and went over to the trash can, took a final sip of his soda — I’ll never forget this — and he looked at all of us and went real loud and stern, “Hey guys. If the f—ing game starts right now, you know who’s batting leadoff? Me. Because I’m ready.”

I was like, “I LOVE YOU, DUDE. YOU’RE THE MAN!” We were all like that: “WE LOVE YOU, BRO!”

That’s an MVP, a Rookie of the Year, a World Series Champion, an All-Star and a should-be Hall of Famer putting that in your head. Like, you better get your s–t together. You’d better be ready.

I’ve told that story to so many people because the leaders are the ones who have no pressure because they’ve prepared harder than anybody in the game. They are more ready than anybody. And that story right there is why Dustin Pedroia did everything he did on a baseball field.

— As told to Jayson Jenks