Fantasy Baseball Waiver Wire: Bucs deliver a pair of priority pickups

It isn't every week that we look to Pittsburgh to fix our fantasy baseball roster problems, but the Bucs have given us a pair of interesting fantasy options in recent days. Let's begin with a flame-throwing right-handed pitching prospect who was pretty clearly ready for prime-time last season...

Roansy Contreras, SP, Pittsburgh Pirates (24% rostered)

Contreras was a moderately interesting pitching prospect entering last year, then went supernova at Altoona and Indianapolis. He dominated the high minors with elevated velocity and a vicious slider, striking out 82 hitters over 58.0 innings while producing a 0.93 WHIP. It's hardly a surprise that he's been so effective in the bigs this season (0.95 WHIP, 10.7 K/9). Have a look at this sorcery:

Contreras just tossed 5.0 scoreless innings against Colorado and will make his next start on Sunday at San Diego. It's kinda wild that the Pirates wasted any of his innings in the minors this season.

Zach Eflin, SP, Philadelphia Phillies (20%)

Eflin has been one of my finest discount-pitcher success stories this season, so you'd better believe we're gonna discuss him here. Did I actually have the guts to start him against the Dodgers on Sunday, when he struck out 12 batters over 7.0 innings and allowed just two runs? No, in fact I did not. But hey, at least I've rostered him. Eflin brings a 1.14 WHIP and 8.5 K/9 into Saturday's start against the Mets. He's a high-K, low-walk starter who shouldn't lack run support in Philly. At the very least, he belongs in the streaming conversation.

Spencer Strider, RP, Atlanta Braves (14%)

Simply put, Strider is among the most valuable non-closing relievers in our game. He throws a zillion miles an hour, he's been nearly unhittable and the guy does it with flair:

Strider has stuck out 37 in 24.1 innings and his swinging-strike percentage is 16.8. Yahoo default rotisserie leagues use an innings-cap, so we need pitchers like Strider who post obscene strikeout rates.

Kole Calhoun, OF, Texas Rangers (32%)

Look, Calhoun may have his flaws as a fantasy option — little speed, meh AVG, many Ks — but there are no questions about his power. He got out to a slow start this season, then blew up in May. Calhoun has cleared the fence six times in his last 11 games. He's just two years removed from a 33-homer season, so, again, the pop is very real. He's a useful option for anyone in need of a power boost.

Cal Mitchell, OF, Pittsburgh Pirates (2%)

Mitchell basically forced the issue this season, raking at Triple-A and earning his call-up to Pittsburgh. He slashed .307/.362/.500 at Indy with five homers, nine doubles and six steals over 34 games. Mitchell's power seems legit...

...and he's opened his major league career going 3-for-9 with a pair of RBIs. He was batting second for the Bucs on Wednesday, so the team definitely believes.

Brendan Donovan, 2B/SS, St. Louis Cardinals (22%)

Donovan has surged in recent weeks, following Paul DeJong's demotion, going 13-for-38 over his past 12 games and reaching base at a .479 clip. He hit .304/.399/.455 across three minor league stops last year with double-digit power and speed (12/19). Given the dual-position middle infield eligibility, Donovan is a potentially useful fantasy piece.