“I was just thinking – middle of the field,” Diaz said.

With the exception of the double he pulled down the third-base line, Diaz did that with a variety of pitches. His RBI single in the top of the ninth inning came off a minor-leaguer, but it also showed other elements of his game. He took second on the throw to home plate. He took third on a wild pitch, and that put him in position to score the Cardinals' fifth run on a meek groundball.

In the field, Diaz has had some superb plays at third base this spring. As he gained strength and comfort with the game last summer at Class AA, he also gained health. His arm, beleaguered by soreness in his debut season, is true, and he’s working to be more consistent. Matheny said there are times when “you see some movements that look like a shortstop.” That’s high praise.

What Diaz did Tuesday was show a good first step.

Back in San Antonio last July, at the team hotel nearby SeaWorld, Rodriguez and Diaz talked about what the waivers meant. Once that sunk in, Diaz took off.