SURPRISE, Ariz. — Tyler Chatwood threw loose and easy during his side session Monday morning, his fastball popping into the catcher’s mitt like small explosions.

Rockies general manager Jeff Bridich stood nearby, watching intently.

“He looks like a healthy pitcher. … He’s throwing like we know he can throw,” Bridich said when asked for his thoughts about Chatwood’s spring thus far.

“Healthy pitcher” is not a phrase commonly associated with the Rockies’ rotation, a unit that routinely posts the highest ERA in National League and usually drags the Rockies into the NL West basement.

Bridich drew criticism from fans and media when he didn’t sign or trade for a veteran starting pitcher during the offseason. Instead, Bridich acquired arms for the bullpen and the future. That means the Rockies are banking on Chatwood and Jordan Lyles to deliver quality innings this season. In Bridich’s mind, that’s a wiser course of action than trading players to bring in a mid- level starter from the outside.

With the season opener against the Arizona Diamondbacks in Phoenix just two weeks away, this is the Rockies’ rotation: left-hander Jorge De La Rosa and right-handers Chad Bettis, Jon Gray, Chatwood and Lyles. Of the five, only De La Rosa has pitched a full season in the big leagues.

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If you think the Rockies’ 2016 season seems to be hanging on a thin thread of hope, you’re right. Still, there is a growing feeling inside the organization that if the starting five can stay on the mound, the Rockies will take a significant step forward from their 2015 season, when they lost 94 games.

“I think we have guys that will compete very well, and they are going to do their part and put us in position to win games,” said ever-optimistic manager Walt Weiss. “We have the right mental makeup in those guys, which is very important because of where we play (at Coors Field).”

Overall, Bridich has been pleased with what he has seen from the starting quintet.

“I think, for the most part, the outings have been very competitive,” Bridich said. “You can’t go crazy, one way or another. You try to keep a rational perspective on it. But, yeah, they have been competitive.”

Here are snapshots of the five starters:

Jorge De La Rosa

De La Rosa, who turns 35 on April 5, says he hasn’t felt this healthy in years. That’s good news for the most accomplished pitcher in franchise history. The left-hander is Colorado’s career leader in wins (78) and strikeouts (877), and his 48 victories at Coors Field are the most in franchise history. But he was not nearly as good in LoDo last season, going 3-2 with a 5.40 ERA in 12 starts. His career ERA at Coors Field is 4.16, so the Rockies need him to rediscover his LoDo magic. He is in the final year of a two-year contract worth $25 million, so a trade could emerge if the Rockies slide early.

Spring training stats: Three games (11 innings), 4.63 ERA, nine strikeouts, three walks, .289 batting average against.

Chad Bettis

By season’s end, Bettis could be the Rockies’ best starter. He certainly was at the end of the 2015 season; he went 3-2 with a 2.97 ERA over his last seven starts. Teammates like Bettis’ bulldog toughness, his quick tempo and his ability to keep them in games.

In the games in which Bettis was good, he was very good. May 29 last season, he took a no-hitter into the eighth inning at Philadelphia. Bettis pitched six or more innings in 12 of his 20 starts, going 6-1 with a 2.66 ERA in those starts.

Spring training stats: Three games (12 innings), 3.75 ERA, eight strikeouts, two walks, .267 batting average against.

Tyler Chatwood

Chatwood, only 26, hasn’t pitched in a regular-season big-league game since April 29, 2014. He has looked sharp in camp but is coming back from his second Tommy John surgery, so there are no guarantees he can thrive for a full season.

Like De La Rosa, Chatwood is not afraid to pitch at Coors Field, where he is 10-4 with a 3.92 ERA in 22 games (18 starts).

Chatwood believes he has tweaked his delivery just enough to be able to stay aggressive, yet save wear and tear on his twice-repaired right elbow.

“Going back to a few years ago, ‘Chatty’ was a bit unbridled as a pitcher,” Weiss said. “He had great stuff, but he’s much more under control now. That comes from maturity and a much better idea of what he’s trying to do now.”

Spring training stats: Four games (11 innings), 3.27 ERA, five strikeouts, six walks, .167 batting average against.

Jordan Lyles

Lyles, only 25, could use a little good fortune. A broken hand in 2014 limited him to 22 starts. Last year, a toe injury that required surgery shut him down after 10 outings.

Healthy now, and rearmed with a split-finger changeup he learned from De La Rosa, Lyles believes he can contribute in a big way.

“I want to stay away from weird injuries and stay on the field and make my 30-plus starts,” he said. “If I do that, I’ll be fine.”

The Rockies would like to see Lyles gobble up innings and save the bullpen. They’d be thrilled to see him crank out quality innings, but whether he can do that at the big-league level remains unknown. His career 23-38 record and 5.14 ERA say he has a lot to prove.

Spring training stats: Four games (11 innings), 5.56 ERA, eight strikeouts, four walks, .273 batting average against.

Jon Gray

The difference in the Gray who made his major-league debut Aug. 4 last season and the Gray who’s been pitching at spring training is night and day. With his fastball command much sharper, Gray, 24, is visibly more self-assured on the mound. His plan to unleash a new curveball has been shelved, for now, but his slider and changeup have been effective this spring.

“What’s been leading the way for Jon has been the fastball command,” Weiss said. “Everything is playing off that. That’s a good sign for him.”

Gray, the third overall pick of the 2013 draft, was limited by an innings/pitch count last year. The Rockies plan to cut him loose this season, but there are bound to be some growing pains. He also has to prove he isn’t intimidated by Coors Field, where he was 0-1 with a 8.27 ERA in his debut season.

Spring training stats: Four games (11 innings), 3.09 ERA, six strikeouts, seven walks, .244 batting average against.

Patrick Saunders: psaunders@denverpost.com or @psaundersdp