It’s not hard to tell why people chant things like “change your speed” at Jorge Julio. The big, hard-throwing reliever is of a type and kind with which Mets fans have enjoyed a painful and intimate familiarity over the years. Like Mel Rojas and Armando Benitez before him, he’s an enormous, broad-shouldered monster who throws in the upper 90s and should never, judging by his looks and his radar gun readings, ever give up so much as a hit. And like them he has a spectacular gift for not only giving up crucial hits, but doing so in a way that makes you think there must be something fundamentally wrong with him.

All of this is pretty much what Julio has been doing his whole career. In 2002, his first full year in Baltimore, Julio ran up a 1.99 ERA in 67 appearances, saved 25 games, and was duly tagged as one of the best up-and-coming relievers in baseball. Each subsequent year saw both his weight and his ERA rise; by last year, the former had gone from about 190 to more like 240, and the latter had climbed to 5.90. He’d lost his closer job and become nothing more than a project, the sort of pitcher worth taking a risk on because of his fastball, but not much more.

In his very first game as a Met, Julio satisfied the worst expectations. Pitching against Washington in a tie game in the top of the 10th, he served up a titanic two-run home run to Jose Guillen, followed that by allowing Nick Johnson to reach first on a passed ball despite the fact that he’d struck out, and gave up an RBI double to weak-hitting utility man Damian Jackson.

Thus began a series of comic misadventures in which he gave up 11 runs in his first 3 2/3 innings, a total that could even have been higher had he not reaped the benefit of a couple of nice defensive plays and a couple of line drives that missed clearing the fences by inches. When Julio somehow managed to go a whole inning against Milwaukee without seeing any numbers light up the scoreboard, he lowered his ERA to 15.43.

Things have been going so well for the Mets that Julio’s shoddy performance sticks out all the more. It’s going to take a long time for him to earn the trust of manager Willie Randolph, and an even longer time for him to gain any credibility with Mets fans. Benitez, for all the lowlights of his Mets career, was, on the whole, one of the very best relievers in baseball during his time in Flushing, and people still talk about him as if he were the devil incarnate.

Worst of all, Julio isn’t merely performing badly. Anyone can accept that; athletes fail from time to time. His problem is that there seems to be something wrong with him. Giving up a lot of runs because you’re going though a dead-arm period is one thing; giving them up because you’re out of shape and seemingly too stubborn to sacrifice velocity for movement is quite another. Most fans, I suspect, loathe Julio for the same reasons they loathed Benitez: They see his failures as ones of character and discipline, and imagine that if they had his physical gifts they would be great baseball players.

Things don’t really work like that. Fans at Shea can chant “change your speed” all they want, but Julio’s hard, 82-mph curveball is a perfectly reasonable secondary pitch, and he’s willing to throw it at various points in the count. His problem is a lot more basic: He doesn’t throw strikes early in at-bats, muscles up on the ball attempting to get strikeouts, and throws straight 95-mph fastballs with no movement right over the plate.

We’ve all found ourselves in situations where we were doing exactly the thing we knew we shouldn’t be doing, but kept on anyway because we couldn’t help ourselves. People panic, they don’t always control themselves well under stress, and sometimes – unbelievably enough – athletes can’t execute what they want to do. Baseball is largely a mental game, but it’s not entirely one. Rest assured that Jorge Julio doesn’t stroll out to the mound with a strategy of throwing a few pitches out of the strike zone and then grooving fat pitches down the heart of the plate. If sacrificing velocity for movement without giving up effectiveness were as easy as it is on Playstation, he and every other pitcher with an arrow-straight heater would do so.

All that said, Julio has the potential to be one of the best relievers in the majors, and with a good pitching coach like Rick Peterson working with him, he may yet become one. But everyone should also be open to the possibility that this is simply who he is, and whether it’s a matter of character, physical ability, inability to handle stress, or some combination of these, he’s never going to be able to put it all together. It’s possible that if you had his gifts you wouldn’t fare any better. Baseball isn’t as easy as pitchers better than Julio sometimes make it look.

tmarchman@nysun.com