Popular waiver wire arms are once again today's topic of discussion. If you're in need of a new pitcher for your staff (and nearly everyone is), both Tyler Mahle of the Cincinnati Reds and Caleb Smith of the Miami Marlins have probably crossed your mind. Neither has much of a track record though, so you may be hesitant to take the plunge.

Both have some promise in their profiles, but are dinged by the quality of their supporting cast. Ultimately, Mahle is likely to be more trouble than he's worth this season, while Smith should be owned in most formats.

Let's take a closer look at the details!

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The Fantasy Jury is Out

Tyler Mahle (SP, CIN) - 19% Owned



Mahle's 4.35 ERA over 39 1/3 IP this season isn't great, but his underlying 3.49 xFIP suggests a quality pitcher. The latter number is rooted in strong K% (25.9%) and BB% (6.8%) numbers, but they seem unlikely to last. Furthermore, his 39% GB% does not bode well at Great American Ballpark.

The first argument against Mahle is the fact that he didn't really strike anybody out in the minor leagues. He debuted in the High Minors for Double-A Pensacola in 2016, tossing 71 1/3 innings of 4.92 ERA baseball. His xFIP (3.60) was better, but hardly enough to intrigue fantasy owners considering his meh 21% K%. Mahle's GB% (40.7%) was only slightly higher than his current mark, leaving him at the mercy of his environment. Pensacola favors hitters (1.016 park factor for runs scored from 2014-2016) by way of boosting HR (1.067 factor), and Mahle struggled with it (14.6% HR/FB).

Mahle returned to the level to begin 2017, throwing 85 IP there. He dominated, posting a 1.59 ERA, 2.73 xFIP, 26.9% K%, and 5.3% BB%. The only thing that didn't change was his ground ball rate, which held perfectly steady at 40.7%. Part of his success was an unsustainable BABIP (.245 vs. .320 the previous year), but he clearly progressed enough to deserve the promotion to Triple-A the Reds rewarded him with.

Mahle was great by surface stats at Triple-A Louisville, compiling a 2.73 ERA over 59 1/3 IP. His xFIP (3.60) wasn't as strong, and his Ks dried up again (21.2% K%). He remained a fly ball pitcher (39.2% GB%), but wasn't hurt by the home run nearly as much as his first taste of Double-A (6.8% HR/FB). Louisville is one of the fairer ballparks in the minor leagues, close to the league average in HR (0.982), hits (1.026), and total runs scored (1.017). His .281 BABIP made sense for a fly ball guy, suggesting that the campaign was a reasonable indication of Mahle's abilities.

Unfortunately, the performance does little from a fantasy perspective. The Ks are not there, and Cincinnati is likely to inflate Mahle's HR/FB on all of the flies he allows. The problem is exasperated by a closer look at his repertoire.

Mahle features a three-pitch mix (fastball, slider, change) plus a show-me curve. He's throwing the curve 1.5% of the time, so it effectively doesn't exist for our purposes. His heater averages 93 mph and has been getting plenty of whiffs (9.2% SwStr%), but lacks the velocity or spin rate (2,164 RPM) to expect that to continue moving forward. Its 58.6% Zone% is impressive, but the pitch isn't as good as it has looked thus far.

Mahle's slider is more of an offspeed fastball than a breaking pitch, boasting a high 50% Zone% but relatively lacking 13.6% SwStr% and 30.5% chase rate. It should help him avoid walks, but it's not a true put away pitch. Mahle's change exists, but its SwStr% (11.3%) is mediocre for an offering with a 43.3% Zone% and 29.1% chase rate. It needs a lot of work to be a viable weapon against MLB hitters.

Thus, we're left with a fly ball pitcher offering middling stuff in a hitter's park. His team is also terrible, preventing him from compiling fluke wins. Mahle is a viable streamer for some road starts, but he's not a fantasy stalwart at this stage of his career.

Verdict: Chump

Caleb Smith (SP, MIA) - 38% Owned

Smith has a 3.67 ERA and 3.54 xFIP over 34 1/3 IP this season, but that is not why he is consistently among Rotoballer's top 10 searches. That has everything to do with his 33.8% K%, an eye-popping number that easily warrants further attention. His walks are high (12% BB%), but you just want to believe in a K% that high. Is it for real?

Smith was Yankee property before this season, so we're revisiting Double-A Trenton (0.928 runs scored, 0.805 HR, 0.993 hits) and Triple-A Scranton/Wilkes-Barre (0.919, 0.879, 0.985) for this analysis. He made his High Minors debut for Trenton in 2015, throwing 130 2/3 IP and compiling a 3.38 ERA against an xFIP of 4.25. His Ks were low (16.6% K%), his BBs were high (9.2% BB%), and fantasy owners couldn't care less.

Smith became interesting when he repeated the level in 2016. His K% increased to 25.1% over 63 2/3 IP while his BB% declined (7.2%). His ERA increased to 3.96 thanks to an inflated BABIP (.344 vs. .280 the year prior), but his underlying xFIP improved to 3.53. The Yankees were impressed enough to let him try Triple-A in 2017.

Smith threw 98 IP for Scranton/Wilkes-Barre last season, where he maintained his gains in both K% (24.6%) and BB% (7.1%). His ERA was a sterling 2.39, though his 3.59 xFIP wasn't quite as confident in the sustainability of his 7% HR/FB or .264 BABIP. Still, it was a solid performance that the Yankees rewarded with some big league innings. They were an utter disaster (7.71 ERA in 18 2/3 IP).

Thus, Smith has a minor league history of favorable strikeout totals, though not to the extent of his performance to date. An analysis of his arsenal reveals that he should continue to strikeout enough batters for fantasy owners to care about him.

Smith is a three-pitch guy, throwing his 93.3 mph fastball 59.6% of the time, a slider 29.4% of the time, and a change 10.6% of the time. His heater offers a strong spin rate (2,407 RPM) that supports strikeouts (8.5% SwStr% and 57.8% Zone%) and pop-ups (53.7% FB%, 36.4% IFFB%). That is a lot of pop-ups, lending credibility to his low .260 BABIP on the season. This is a very good pitch.

His heater's high Zone% also sets up two legitimate wipeout offerings. His slider could use a slightly higher chase rate (37.5% this year), but performs very well otherwise (18.3% SwStr%, 37.8% Zone%). His change is seldom chased outside of the zone (27.9%), but induces plenty of whiffs (18.5% SwStr%) when it is. It's definitely Plan B to the slider's Plan A, but few repertoires have two offerings with an 18% SwStr%.

Moving forward, Smith's K% is likely to fall to something like 27%--not as strong as it has been, but still really good. Considering his minor league history, a corresponding decrease in walks could keep his K/BB roughly where it is now. Wins will be hard to come by on a glorified expansion team, but this 27-year old is the real deal.

Verdict: Champ

More 2018 Player Outlooks