Christian Vazquez is the established starter, but who will be his backup?

Third in a series.

Christian Vazquez takes pride in catching every game. He wanted to make a point of that in 2019: play as much as possible and be an impact player for the Red Sox.

In 2018, Vazquez split time with veteran Sandy Leon and started 74 games at catcher, a career high at the time. Last season, Vazquez became the first Sox catcher since Jarrod Saltalamacchia in 2013 to catch 100-plus games (Saltalamacchia caught 106 times that year).

“I love to be in the lineup,” Vazquez said toward the end of the season. “I want to be there every day. I hate to be on the bench. I like to play.”

Before last season, Vazquez was considered a defensive catcher, but in 2019 he had a breakout season at the plate. Vazquez hit .276 with 23 homers and a .798 OPS, and finished the season ranked in the top five for catchers in both homers and batting average (minimum of 400 plate appearances).

He didn’t always drive the ball, so during the 2019 offseason, Vazquez revamped a swing that often produced groundballs into one with more launch angle.

“His approach to the ball and the movements of his body have changed,” former Sox assistant hitting coach Andy Barkett said last year. “He used to kind of cut the ball, more of a direct path to the ball. He would be able to hit it all the time but his barrel a lot of times wouldn’t stay in the zone long enough.

“Now he’s really getting behind the ball early and able to stay through the ball and hit it with backspin.”

At times, Vazquez became overzealous, chasing pitches at a 35.2 percent clip and striking out 101 times in 521 plate appearances.

“With Christian, it was amazing that he was hitting the ball harder,” manager Alex Cora said at the end of last season, “but there were certain times with Christian that a man was on third with less than two outs, I don’t know how many times he was able to drive it in.”

While his offense improved, Vazquez’s defense took a step back. Vazquez led the American League with nine passed balls and had the third-most in the majors. In certain games, he was lazy with his feet, electing to backhand certain pitches in the dirt instead of moving his body to get in front of it. It wasn’t until September that Vazquez’s defensive prowess was more evident, and he was a finalist for a Gold Glove.

The tools never left Vazquez, who has one of the better arms at his position. Most importantly, the Sox brass is bullish on his game-calling and his ability to mix the data with in-game feel or adjustments. If he can produce another solid offensive campaign in addition to maintaining his defense throughout the course of the season, he could be among the best two-way catchers.

Vazquez is the likely starter next season. The bigger question is who can be his backup? Blake Swihart failed to take hold of one of the catching spots and was designated for assignment in April. That left Leon as the backup, but his offensive struggles proved to be a huge hole in the Sox lineup. In 191 plate appearances, Leon hit just .192 with a .251 OBP and .297 slugging percentage. In 2019 and 2018 combined, Leon hit .183 in 479 plate appearances.

The Sox are no longer tethered to having certain pitchers work with Leon. Rick Porcello is a free agent and Vazquez worked more with Chris Sale this season than he did in the past. Leon made $2.475 million last year and might represent too big of an arbitration number to bring him back.

Sox catching prospect Kole Cottam is still some time away from reaching the majors. Jhon Nunez spent time in Double A last year and the Sox re-signed him to a minor-league deal, but he, too, isn’t ready.

The Sox could re-sign Juan Centeno, who was recently outrighted and then elected free agency. Centeno has familiarity with the coaching staff, Cora, and some of the Sox pitchers.

It’s worth noting that new chief baseball officer Chaim Bloom has a knack for finding defense-first catchers with elite pitch-framing ability and sticking with them despite some offensive lulls.

Jose Molina, for instance, had 834 plate appearances over three years with the Rays from 2012-14 despite hitting just .213 in that span. Bloom acquired Mike Zunino, and even though he hit just .165, he had an immediate impact on the Rays pitching staff.

Could the Red Sox nab someone like that?

The Sox have Vazquez under contract on what could become a team-friendly deal — he has two years and $10.45 million remaining and the Sox have a $7 million option for 2022 — but his understudy is the one question that looms large.

CATCHER OUTLOOK

Primary 2019 starter: Christian Vazquez

Projected 2020 starter: Christian Vazquez

Major league depth: Sandy Leon.

Prospects to watch: Kole Cottam, Jhon Nunez.

Around the horn

Part 1: It’s all about the rotation if Red Sox hope to rebound in 2020

Part 2: How should Chaim Bloom approach changing the Red Sox bullpen?

Julian McWilliams can be reached at julian.mcwilliams@globe.com. Follow him on Twitter at @byjulianmack.