ST. LOUIS — Trying to make up the ground they gave up in losing 13 of their previous 19 games since returning from Houston, the Rays on Friday added a veteran infielder with postseason experience to their roster and put him right in the lineup for the 7-3 victory over the Cardinals.It's just that signing Danny Espinosa hardly seemed like the move that will push them over the top in the American League wild-card race.That's in part because Espinosa doesn't exactly inspire, a 30-year-old who has already been released this season by the Angels and Mariners after hitting a combined .164 with five homers, 31 RBIs and a .516 on-base plus slugging percentage, meaning whatever value he has in his versatility, slick glove, experience, and value, making the minimum.RELATED: Rays overcome short outing by Jake Odorizzi, beat Cardinals. And in part because in doing so, the Rays sent down likable and hard-working rookie Daniel Robertson, who impressed just about any time he got on the field with his ability to make dazzling plays.So why do it?Because the Rays feel Espinosa, who started for the Nationals during much of seven seasons there, is actually as good or even better a defensive player than Robertson, with additional versatility in also playing first and leftfield and in being a switch-hitter.And because Robertson wasn't exactly doing much offensively himself. He's hitting .211 with five homers, 18 RBIs and a .642 OPS and could benefit, they felt, especially with the six weeks he missed on the DL , from playing every day for at least a few weeks with Triple-A Durham, which is headed to the International League playoffs.In short, because it's what the Rays do, constantly weighing the present and the future.RELATED: Rays journal: Some get creative with nicknames on uniforms. "We want to be as competitive as possible while also doing what we can to provide our young players the best opportunities to maximize the development of their talent," general manager Erik Neander said Friday night.Obviously there is a potential financial component to this type of move as well, though the payoff truly might not be until after the 2022 season. And that, too, is part of the battle the Rays are always waging.If Robertson were to stay in the minors for at least 20 days, then he won't get credit for a full year of big-league service, which means — assuming he came up at the start of next season and never got sent down again — he wouldn't be a free agent going into 2023 but 2024. (Also note, they had sent him down in June before a neck injury surfaced.)Now critics and skeptics can point out — somewhat fairly — that the Rays should be less concerned about something six years from now and more concerned about winning over the next six days. (Or that this is all just further scrambling after how badly the decision to trade Tim Beckham to Baltimore and keep Brad Miller has worked out.)RELATED: Beat writer Marc Topkin's takeaways from Friday's Rays-Cardinals game. That's especially since the series against the Cardinals and the American League wild card-contending Royals take them right to the Aug. 31 deadline for postseason eligibility and — with a bad week — could lead to them deciding whether to flip some of their own players and become sellers.But this is how they operate. And given their revenue issues and attendance and resulting self-imposed budget restraints, it is how they are going to continue to while also putting a focus on developing their young players and putting a premium on the time they have them under control in the majors.It's easy for fans to question why they haven't called up top prospects such as infielder Willy Adames and starter Brent Honeywell and assume it all has to do with not starting their service time clocks, which can lead to significant future costs in terms of arbitration and free-agent eligibility.And it's just as easy for the Rays to say neither is yet ready for the majors.As impressive as Honeywell has looked at times, he is a good but not dominant 11-8 with a 3.80 ERA at Triple A, hardly helping his case for a September callup by getting knocked out in the first inning Friday. And as promising as Adames appears as a 21-year-old playing shortstop at Durham and hitting .273 with nine homers, 54 RBIs and a .774 OPS, he has 25 errors and no place to play regularly in the majors since Adeiny Hechavarria has his position.The Rays have made these kind of moves before, even earlier this season when they acquired Trevor Plouffe in June to provide infield depth rather than call up Patrick Leonard or Adames then.And ditching Plouffe Tuesday, they got him through waivers and will send him to Triple A for a week then bring him back up, still convinced he can help them.Now they feel the same way about Espinosa, who was in the lineup Friday night.Marc Topkin can be reached at [email protected]. Follow @TBTimes_Rays.