It makes for a delicious discussion how a couple of annual contenders, the Cardinals and Texas Rangers, could fill present needs and fortify future lineups by swapping, straight up, two of baseball’s elite prospects. The notion Cardinals standout Oscar Taveras and Texas’ Jurickson Profar — two familiar names with galactic potential — could be exchanged in the rarest of moves fits all the talking points of the juiciest trade rumor. It must be noted, though, who isn’t talking about it. The two general managers have not. They must know better. “It makes all sorts of sense and there is no way to do it,” said an official with an American League team who has scouted both players but is not authorized to talk publicly about other clubs’ players. “The Cardinals need a shortstop. The Rangers need an outfielder. The answer is there for both for years to come. You just can’t do it. You can’t be the guy who is wrong if one works out and becomes a star as expected and the other doesn’t. “Then you’re the new Brock-for-Broglio guy.” Like any juicy trade rumor, hypothetical or actual, this one has big names, bigger potential — and the biggest risk. It links the top middle infield prospect in the minors with the Cardinals’ top prospect. Many consider Taveras to be the best hitting prospect in the game. At its root, it’s a notion spawned from supply and demand. Texas just signed All-Star shortstop Elvis Andrus to $120-million extension that effectively blocks Profar from his highest-value position, all while the Rangers were known shoppers for an impact outfield hitter last winter. The Cardinals want to open playing time for Matt Adams, but doing so would require moving Allen Craig to right field, thus filling the spot reserved for Taveras in 2014.