DENVER -- Rockies manager Bud Black watched catcher Elias Díaz grow from question mark to workhorse. The three-year contract Díaz agreed to Thursday, valued at $14.5 million according to a Major League source, serves to elevate him to mainstay.

The contract covers Díaz‘s final year of arbitration and covers his first two years of free-agent eligibility. One could say 2021 for Díaz -- whose agreement went public a day after his 31st birthday -- went much the way it did for the Rockies. The start was awful, but there was definite, and at times, dramatic improvement over the final months.

In April and May, Díaz, in his first chance at regular playing time, hit .125 with one home run as he and equally struggling rookie Dom Nuñez flailed while trying to establish themselves. But from June 1 to season’s end, Díaz, who joined the Rockies in 2020 after five seasons with the Pirates, batted .283 with all but one of his 18 homers, and he posted a .346 on-base percentage and .550 slugging percentage.

Díaz’s final 18 games produced a .339 batting average with three home runs, five doubles, 10 RBIs and nine runs scored.

His defense in the running game was also strong. His 42.1% caught-stealing percentage ranked second to Royals star Salvador Perez’s 43.9% among catchers with 60 or more starts.

“It’s a combination of the physical strength, the durability and the work capacity, and also mentally being able to withstand the rigors of catching, and mentally, feeling fresh to know that you’re fine to play that many games,” Black said. “It’s a mindset for a guy who plays every day, never talks himself into being tired or talks himself into, ‘I need a day off.’”

The Rockies signed Díaz before the 2020 season, after the Pirates non-tendered him. A key was Díaz accepting the decision from Black and bench coach Mike Redmond, a former Major League catcher, to have him begin the shortened '20 season at the alternate training site to complete fundamental work in his receiving and throwing, while Tony Wolters and Drew Butera took the big league playing time. But by hitting .235 with two homers in mostly late-season opportunities, Díaz earned his chance in ’21, when the club did not retain Wolters and Butera.

During Díaz’s 2021 struggles, the Rockies urged him to stay with a simplified hitting approach. The hits arrived late, but they made it.

Díaz’s 18 homers were tied for fourth in club history among catchers and they were the most from the position since 2013 (Wilin Rosario, 21). Díaz also delivered three walk-off hits, including an Aug. 21 homer against the D-backs that was Colorado's first walk-off on an at-bat of at least 10 pitches.

Going into 2021, it wasn’t clear if the right-handed-hitting Díaz or the lefty-swinging Nuñez would be the main guy. Now, Díaz is the clear starter, and Nuñez is playing regularly for Indios de Mayagüez in the Puerto Rican Winter League (hitting .276 with one home run in nine games through Wednesday night).

The Rockies have also signed two of their potential free agents, first baseman C.J. Cron (two years, $14.5 million) and righty reliever Jhoulys Chacín (one year, $1.25 million), and reached extensions with Díaz and righty starting pitcher Antonio Senzatela (five years, $50.5 million).