Aroldis Chapman struck out 21 batters in 15 2/3 innings in the postseason, allowing only 11 hits, and he had moments of total dominance, when his 101 or 102 mph fastballs overwhelmed opponents.

But in the National League Championship Series and in the World Series, two of the relievers generally regarded as his performance peers -- Kenley Jansen of the Dodgers and Andrew Miller of the Indians -- pitched for teams the Cubs faced, and Chapman suffered in comparison in the eyes of rival evaluators.

By the end of the World Series, some scouts had concluded that Chapman isn't as comfortable pitching multiple innings as Jansen and Miller, and probably is best suited for working when he can be given a clean slate: no runners on at the start of an inning. Chapman has had eight postseason save opportunities in his career and has blown four of them, and in the 2016 playoffs and World Series, he allowed five of 11 inherited runners to score.

None of this will prevent Chapman from getting an enormous contract from his next employer, because even if he's not quite as good as Miller, Jansen and Zach Britton, he's still among the best relievers. After the 2011 season, Jonathan Papelbon agreed to a four-year, $50 million deal with the Phillies, and no contract for a reliever has surpassed that -- yet. Chapman and Jansen, both free agents, are expected to sign for far more this winter, and Mark Melancon may approach that mark as well.

But some evaluators have wondered about how Chapman will evolve in the years ahead as he inevitably loses velocity. Chapman will turn 29 this winter, and through his diligent training, he is enormous, incredibly strong and gifted. He seems to have the physical infrastructure to throw really hard for a long time. "But I think we saw [in the postseason] that when he's throwing 98 mph or 99 mph, he's a different pitcher," one evaluator said. "Hitters had better swings against him."

The at-bat cited by several evaluators as a sign of things to come was Rajai Davis's eighth-inning plate appearance in Game 7 of the World Series. Through the seven pitches Davis saw, it became apparent that Chapman's stuff was diminished by all of the work he had done in the postseason, including 1 1/3 innings the night before in Game 6. From pitch to pitch, Davis -- choked up on the bat -- seemed to take improving swings against Chapman before he golfed a fastball thrown down and in for a game-tying homer.

That pitch was 98 mph.

According to FanGraphs, Chapman was the only reliever to average 98 mph or higher during the 2016 season, so that kind of velocity, a diminished Chapman, is still incredible. "But most pitchers in that spot probably would've thrown a slider, and [Davis] would've had no chance, because he was so geared up for the fastball," one official said. "If you're Chapman, though, are you going to throw anything other than your best pitch? You're going to throw your fastball."

Over time, Chapman will have to learn to use a greater array of pitches and pitch more to scouting reports. His evolution might have to be similar to that of Justin Verlander, who routinely overpowered hitters for much of his career, without regard to scouting reports, until hitters began to jump on his fastball. Then, during the 2015 season, Verlander adapted, using the information available to him to attack the weaknesses of hitters, while altering his slider to give it a tighter break, and through those changes, Verlander became one of the most best starters in the AL again.

A scout says he thinks Chapman can make a successful transition in the years ahead. Chapman threw his slider on 15.7 percent of his pitches last season. "He's got a good slider," the scout said. "He just needs to know how to use it, when to use it. And I think his command is pretty good."

Said another evaluator: "There hasn't been any need for him to spot the ball because he can throw it past hitters without worrying about that. But that's something he's going to have to do [in the future], and I think he'll be able to do it."

The team that gives him $70 or $80 million or more this winter, in a deal that will carry Chapman into his mid-30s, will have to believe that.