While a lot of the focus of discussions this time of year is on which prospects contending teams should trade for which stars, quite often simply using their own top-performing prospect is a superior choice for a ballclub in win-now mode.
Nine players called up since Tax Day (April 15, for those outside the U.S.) already have been worth at least a half-win's worth of WAR. Some of these players are having real pennant race impacts so far: Gleyber Torres, Austin Meadows, Ronald Acuna Jr., Jaime Barria, Seranthony Dominguez and Nick Kingham are all making a difference on teams that have been competitive. These aren't players getting opportunities with rebuilding teams just throwing stuff at the wall and seeing what sticks. Plus, Juan Soto! He just missed my 0.5 WAR cutoff, but the kid is hitting .312/.404/.571, so we have to mention him.
Teams are far from being out of homegrown talent to lean on, whether they're contending or pretending -- or just want to play spoiler. Whether it's a top prospect or a lower-ceiling player in the high minors who can make a short-term impact, more reinforcements are on the way. With each of these players, these are their projected performance at the MLB level if they were called up today; let's hope they get the opportunity to make good on them soon.
3B Vladimir Guerrero Jr., Toronto Blue Jays
The Vladimirovich wasn't arriving quietly, destroying the Eastern League to the tune of a .407/.457/.667 triple-slash line with 11 homers when a knee injury gave Double-A pitchers an opportunity to sleep peacefully for the next four weeks while he's out. Before that setback shelved Vladi Jr. for the rest of June, the official explanation for his continued presence in the minors was of the "improve his defense at third" variety, given that his glove isn't as far along as his bat.
But the point of calling up Vlad once he has recovered is not just to get him some major league seasoning but also to help the team as soon as possible. After a 9-19 May, the Blue Jays drifted out of obvious contention, and at 33-38, they need to add a lot of wins, given that they're currently 13 games behind in the race for the American League's second wild card. Plus, they aren't playing in one of the weak divisions, so the wild card is their only real ticket to October.
If the Jays aren't yet willing to throw in the towel on the 2018 season, then getting any win from wherever they can is crucial if they want to overcome their odds against September relevance. Kendrys Morales, the primary designated hitter, has a 75 OPS+ entering Sunday. If you really want to win now, do everything you can to win now. If it fails -- as is likely -- there's nothing keeping you from sending Vlad back down to Triple-A to work on third base and to concentrate on that over the winter.
ZiPS projection for the rest of 2018: