Jordan Weems said his conversion from catcher to pitcher in 2016 in the Red Sox organization was a leap of faith.

It was rewarded Sunday, when the hard-throwing right-hander landed on the As season-opening roster.

It was an emotional one, for sure, Weems said Tuesday of his reaction to receiving the news from As manager Bob Melvin. Its been a long, tough grind.

Weems, 27, was drafted as a catcher by the Red Sox in 2011, but his career stalled due to his hitting. The Red Sox tried him briefly at first base, but thought the 6-foot-3, 175-pounders arm and tall, lanky build might be better suited for the mound despite the fact he didnt pitch even in high school. This spring, Weems arrived in As camp as a non-roster player on a minor-league deal.

His goal, Weems said, was to show the coaching staff and the guys in that clubhouse that I belong.

That meant throwing plenty of strikes with a mid- to high-90s fastball, Weems said, then mixing in his split-finger fastball and slider to show them I could strike out some guys, too. Weems impressed the As in the spring and continued to do so when the team reconvened for training camp.

He earned his way here, Melvin said this week. You hear the feedback from the hitters we can see all we want, see the numbers and the strikeouts and he throws hard, but when you get the feedback from the hitters, its impressive (given) where hes come from.

He was pretty excited about hearing the results (Sunday). And he should be proud of himself because baseballs a tough gig, and to switch positions on the fly like that and make it to the big leagues is really impressive.

On a video call Tuesday, Weems recalled his sudden transition in 2016. He was playing first base with Double-A Portland (Maine), and hitting .119, when the Red Sox told him they wanted him to pitch. A week later, Weems was back at the Red Sox spring training facility in Fort Myers, Fla., throwing off a mound. After two weeks, he was facing live hitters.

In his four seasons as a minor-league pitcher, Weems was 13-8 with a 3.87 ERA, 208 strikeouts and 104 walks in 200 innings.

Weems said it helped that, as a catcher, he had spent time around pitchers and watched them work on mechanics and grips. That continues now: Weems said he switched from throwing a changeup to a splitter late last season and asked As reliever Joakim Soria about his own grip and use of the pitch.

Im behind the eight-ball with a lot of this stuff, Weems said. So Im trying to learn as much as I can.

Pitching coach Scott Emerson recently noted Weems ability to spot pitches including fastballs in the upper half of the strike zone is pretty good for a guy who hasnt done much pitching. Right-hander Daniel Mengden said he didnt know much about Weems previously, but hes a hard-working guy and he throws the ball hard.

Its one of those things where you work hard and put your mind to something, you can do it, Mengden said, and hes grinded and worked hard and hes earned himself a spot.

Melvin said that with Weems, you cant help but think about former As reliever Sean Doolittle, who converted from first base in the minors. Weems pointed to Dodgers reliever and former catcher Kenley Jansen as another position player-turned-pitcher. You just know theres other guys out there, he said, so why cant I be the same?

His catching past gives Weems a unique view of some As pitchers. In 2013, Weems was teammates with current As starter Frankie Montas and reliever J.B. Wendelken at Class A Greenville. Weems smiled when he recalled Montas, then 20: All he cared about was how hard he threw so he was a little sporadic back in the day. I always give him a hard time about that.

Weems and Wendelken go back even further; the Georgia natives played travel ball together as teenagers before being drafted by the Red Sox a year apart, Weems said.

I caught those guys in Greenville, Weems said, and we think its pretty funny how now Im a pitcher and were in the same clubhouse doing the same thing.

Matt Kawahara covers the As for The San Francisco Chronicle. Email: mkawahara@sfchronicle.com Twitter: @matthewkawahara

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Converted catcher Jordan Weems ready to pitch in for As - San Francisco Chronicle