If looking for hitters on the waiver wire is a dicey proposition this time of year, finding a worthwhile starting pitcher is a verifiable minefield. Everyone has been looking for pitching all season, and there just hasn't been enough of it to go around. Owners in need of arms should still look to recent call-ups to provide the spark they require, but you'll probably need to pounce before your target has any MLB success.

Lucas Sims of the Atlanta Braves has made two starts thus far, and the results haven't been encouraging. Still, his minor league track record suggests that he may be of use in the near future. Reynaldo Lopez is set to permanently join the Chicago White Sox rotation on August 11, offering some upside over the next two months. Let's take a closer look at the pros and cons of rostering these relative unknowns.

Ownership rates provided are from Yahoo! leagues.

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The Fantasy Jury is Out

Lucas Sims (SP, ATL) 4% Owned

Sims is 0-2 with a 5.25 ERA and 5.51 xFIP since joining the big league rotation, earning little fantasy attention for his efforts. He's been extremely susceptible to the long ball (18.8% HR/FB) and hasn't contributed anything to the strikeout category (12% K%). The 23-year old has an extensive minor league history suggesting that he is much better than he has shown so far, presenting a buying opportunity for fantasy owners desperately searching for upside.

Sims threw 115 1/3 IP at Triple-A before his big league debut, compiling a 3.75 ERA, 3.37 xFIP, and 28.1% K% on the farm. His 7.7% BB% wasn't great, but marks a significant improvement over his previous minor league work. Sims managed to walk 15.4% of the batters who faced him in his first taste of Triple-A last season (50 IP), contributing to a 7.56 ERA despite a strong K% (24.1%). The underlying xFIP (4.48) wasn't good, but suggests that he wasn't quite as overwhelmed as the raw ERA suggests.

Sims has a BB% of 4% at the major league level, so his control continues to trend in the right direction. He has also generated strikeouts at every minor league stop, so there is no reason to think that a 12% K% represents his true ability. This conclusion is supported by the hurler's fastball, which has generated an 8.5% SwStr% over his two starts so far. It seems safe to project more strikeouts moving forward, leaving homeritis as the only reason to avoid Sims in fantasy.

Sims earned his initial promotion to Triple-A by dominating Double-A. He pitched to a 2.67 ERA (4.16 xFIP) over 91 IP there last year, striking out 25.8% of the men who faced him against a BB% of 14.1%. The walk rate was high, but Sims limited the damage it caused with a HR/FB of 3.3%. That may seem fluky, but he managed an even better HR/FB (2.5%) in 47 2/3 IP at Double-A in 2015. This homer suppression ability escaped him in Triple-A (16.2% HR/FB this year, 19.7% at Triple-A last year), but there is at least some hope it will eventually transfer to the majors.

Sims needs a strong HR/FB to succeed, as he looks like a fly ball guy. His FB% has exceeded 40% in every minor league stop since his first taste of Double-A in 2015, including a 42.1% mark so far at the MLB level. Data on Atlanta's new SunTrust Park remains limited, but early indications suggest that it favors power hitters. Sims will also have to deal with a poor defensive outfield in Atlanta, as Nick Markakis (-5 DRS) is bad while Matt Kemp (-11) is atrocious. Ender Inciarte is fantastic (10 DRS), but his teammates negate the defensive value he provides.

There is no way for Sims to sustain his .243 BABIP against considering the outfielders behind him, but fly ball specialists tend to beat the league average. This is especially true if they can generate pop-ups, something Sims hasn't done yet in the majors (0% IFFB%). Again, his minor league history tells a different story. His 14.8% IFFB% at Triple-A last season was acceptable, but it surged to 30.8% over a significant sample at Triple-A this year. The resulting .275 BABIP is likely Sims's upside in the majors, even if he is unlikely to post an IFFB% above 30% at the highest level.

The Braves are bad, so wins could be hard to come by even if Sims starts performing up to his minor league standards. There is also some possibility that Sims never figures out how to adapt his game to the highest level. On the bright side, he has a starter's repertoire (heat, sinker, slider, change, curve) and a minor league track record of doing exactly what he would need to to succeed in the majors. He'll probably be volatile this year, but the occasional strong outing is better than the mediocrity otherwise available on waivers.

Verdict: Champ

 
Reynaldo Lopez (SP, CWS) 20% Owned

Lopez hasn't thrown an MLB pitch yet this season, but he profiles similarly to Sims. He has a 3.79 ERA (3.84 xFIP) over 121 IP at Triple-A this year, boasting a K% of 25.4% against a 9.5% BB% on the farm. His .269 BABIP seems favorable, but Lopez is a fly ball guy (42.8% FB%) who should be able to limit BABIP. His IFFB% of 31.4% suggests an ability to induce pop-ups, maximizing the value of a fly ball profile.

Lopez has more of a pop-up track record than Sims, producing a FB% of 46.7% and 26.2% IFFB% in 33 IP at Triple-A last season. The resulting .174 BABIP is unsustainable against major league hitters, but he also induced plenty of pop-ups (38.3% FB%, 18.1% IFFB%) over a larger sample (76.1 IP) at Double-A before his initial promotion to Triple-A. His BABIP was elevated at Double-A (.320), but his 3.18 ERA, 2.81 xFIP, and 30.4% K% at the level suggest that the elevated BABIP was not an issue.

Lopez also did a reasonable job limiting homers on the farm. His 11.7% HR/FB at Triple-A this year is roughly league average, while his 9.7% HR/FB at Double-A last season was a little bit better. Successful fly ball specialists need to run below average HR/FB rates, and there is reason to believe that Lopez can do it.

The strong performance on the farm earned Lopez a 44-inning MLB debut with the Washington Nationals last season. The 4.91 ERA he produced wasn't pretty, while the underlying 4.52 xFIP wasn't much better. His 20.9% K% wasn't special, while his 11% BB% was too high. He did not produce a lot of flies (35.3% FB%), nor were a lot of his flies of the pop-up variety (10.6% IFFB%). In short, his peripherals looked nothing like his minor league game plan.

There were some positives from his big league stint though. He averaged 96.7 mph with his fastball, proving his potential as a power pitcher. He also flashed a plus curve, which produced a 16.3% SwStr%, 45.1% Zone%, and 48.4% Z-Swing%. The Z-Swing% is particularly encouraging, as it means that batters took it for a strike more than half the time it was in the zone in addition to the swinging strikes it generated. His change may eventually develop into a wipeout pitch (42.3% chase, 14.5% SwStr%), but the whiff rate was a little too low for a pitch with a 37.4% Zone%.

Guaranteed Rate Field can be a tough place to be a fly ball pitcher, but the 3.7% Brls/BBE Lopez allowed in his MLB stint last year suggests that he may be able to survive it. The White Sox also improved their outfield defense by shipping Melky Cabrera and his -7 DRS out of town. Adam Engel (-5) isn't great either, but Leury Garcia (four DRS) and Avisail Garcia (three) make the unit slightly above average as a whole.

A fly ball arm in a hitter's paradise is definitely risky, but there is significant upside here. Wins will again be hard to come by, but owners looking for Ks and WHIP could do far worse than this 23-year old prospect.

Verdict: Champ

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