"We worry about the opportunity for October later," manager Mike Matheny said. "Right now, we have a lot of games we have to win and figure out how to be a little better in our 'pen. I think he's going to give us a little flexibility to achieve that."
Nicasio, 31, has made a National League-high 67 appearances this year. The first 65 of those came with the Pirates, who lost the right-handed reliever to the Phils after placing him on irrevocable outright waivers at the end of August.
That decision, Pirates general manager Neal Huntington explained at the time, was made in an effort to try and find a landing place for Nicasio with an American League contender. What Huntington said he hoped to avoid was exactly what happened -- that Nicasio ended up with a team considered to be a "direct competitor" to Pittsburgh.
The Bucs, who received only salary relief when the Phillies took Nicasio, will get to see their former setup man this weekend in St. Louis, where the two clubs will meet in a three-game series.
Nicasio, who was expected to join the Cardinals in San Diego late Wednesday, has posted a 2.79 ERA and a 1.09 WHIP over 61 1/3 innings this season. He's struck out 16, walked 18 and held opponents to a .218 batting average. Nicasio's 21 holds rank fifth in the NL.
He'll fit in as a late-innings option for Matheny, who is also open to using Nicasio in save situations.
"Just throw him into the mix and see how he fits," Matheny said. "We don't really have roles down there. We'll get him in there and realize that he's a guy who can probably do multiple things for us."
Alvarez, 22, spent the majority of the 2017 season with Double-A Springfield, where the middle infielder hit .247/.321/.382 in 56 games. Alvarez, who signed with the organization out of the Dominican Republic in 2011, had been added to the team's 40-man roster last fall in order to be protected in the Rule 5 Draft. Nicasio will now take that roster spot.
• Class A Advanced Palm Beach swept its Florida State League semifinal series against Fort Myers to become co-champions of the FSL. The league previously announced the cancellation of its final series because of Hurricane Irma.
• Pitcher Daniel Poncedeleon, who required emergency surgery after being struck in the head by a line drive in May, rejoined Triple-A Memphis on Wednesday for the start of its Pacific Coast League playoff run.
• Jack Flaherty, who started for the Cardinals on Wednesday night, began the day by being named the PCL Player of the Month for August. Flaherty went 4-1 with a 1.97 ERA in 29 strikeouts in 32 innings for Memphis last month.