Typically when a team claims a player off waivers, he's considered the guy at the end of the bench or the last guy out of the bullpen. Rarely do teams put legitimately decent players on non-revocable waivers, but every once in a while a Joel Peralta (2010 by the Rays) is mysteriously put on waivers. Peralta had a near-2 ERA with good secondary numbers in 2010 with the Washington Nationals as a reliever, yet found himself without a job. The Rays picked him up and rode him as a setup reliever for several years through his mid-30s.
You know that I'm eventually going to bring up Sam Fuld and Jordan Schafer, but they were no Joel Peralta. There was no mystery as to why they lost their employment. For the Oakland Athletics, Fuld started the season on the major league roster because Craig Gentry did not due to injury. Once Gentry, the preferred choice to be the team's 4th outfielder was healthy, Fuld was no longer needed and he was cut loose. A career .238/.314/.334 hitter, he could draw walks but didn't offer much with the bat. His defense was solid in the corners but he couldn't man center field well. Meanwhile, Gentry was an excellent defensive center fielder and while he didn't walk as much or display any extra-base power, he was still easily superior to Fuld.
The Twins claimed Fuld simply because they needed a player that could man center field, even if he wasn't exactly great at it, but the move ended up working brilliantly. Fuld did miss time with a concussion in the middle of the season, but that didn't prevent him from going on a hot streak in July. Also, the interesting fact was that he rated extremely well defensively in center field. Yes, defensive statistics aren't very reliable in small samples, but for a third of a season Fuld covered the outfield very well. Along with a .274/.370/.354 line at the plate, Fuld racked up 1.5 WAR in just over 50 games. Over a full season at that pace, Fuld would have contributed 4 1/2 wins, an absurd amount for a player that was on the waiver wire just a few months earlier.
Of course, the Twins took advantage of Fuld's hot streak and traded him back to the A's for Tommy Milone. While the trade hasn't looked great thanks to Milone's struggles after leaving Oakland, Fuld returned back to his normal self upon rejoining the Athletics. With Fuld's departure, the Twins again wanted a defense-first outfielder and this time they found it in Jordan Schafer. Like Fuld, he was also designated for assignment, but instead of being replaced by a teammate returning from the disabled list, he was dropped because the Atlanta Braves' trade acquisition of super-utility player Emilio Bonifacio.
Schafer was once a top prospect that never had lived up to the hype. He didn't show much with the bat and his defense didn't rate well. However, he did demonstrate that he was an accomplished basestealer, stealing at least 20 bases in four consecutive years now despite being only a part-time player. When he was designated for assignment by the Braves, he had spent the whole season with the team but had only mustered a .163/.256/.213 triple-slash. Even though he was drawing walks in 10% of his plate appearances, it wasn't enough to overcome his poor average and the Braves cut bait. The Twins picked him up and suddenly he found his stroke at the dish, hitting .322/.390/.400. While a BABIP near .400 helps, Schafer's found a way to cut his strikeouts significantly, striking out in only 13% of his at-bats whereas his career rate was at 25.5%. His defense in left field (his main position with the Twins) has been above-average, and it all has added up to make him a 0.8 WAR player in just 30 games.
With some simple math, we can see that the Twins have racked up some huge value out of two backup outfielders that were acquired for nothing. In roughly 80 games from Fuld and Schafer, the Twins have received 2.5 WAR. With some more simple math, that's about 5 WAR in a full season. Yep, they would have provided nearly as much value as Phil Hughes and more than Brian Dozier if they could maintain it for an entire season.
Just how unprecedented is that value that was accrued by Fuld and Schafer for the Twins? Well, let's look at all the Twins' midseason waiver claims in the Target Field era with their WAR and games played from that season.
OF Sam Fuld (53 games, 1.5 WAR)
OF Jordan Schafer (29 games, 0.8 WAR)
OF Kenny Wilson (0 games, 0.0 WAR)
Clete Thomas (12 games, 0.0 WAR)
Erik Komatsu (15 games, -0.4 WAR)
Esmerling Vasquez (0 games, 0.0 WAR)
Randy Flores (11 games, -0.4 WAR)
So yeah, just the fact that the Twins have gotten even positive value from either player is unprecedented over the past 4+ years. Whether it's by luck or excellent scouting, we can safely say that the additions of Fuld and Schafer have paid off with far more value than I think anyone could have predicted.