In a year where seemingly any pitcher whose arm is intact has made a start for the Mariners, Sam Gaviglio has risen above The Pile and cemented himself as a solid depth option. Including last night's start against Houston, he has provided the club with just over forty-five innings of 3.38 ERA ball. He has been a lock to go at least five innings per start, and is a moderately big reason the club has managed to stay in the race.

Given his AAAA sinker-led arsenal, however, that ERA feels fluky. He doesn't miss many bats (only a 6.1% swinging-strike rate), his sinker sits at an average of 88.6 MPH, his command comes and goes, and to top it all off, he gives up a lot of hard contact - he has managed just a 13.2% Soft% on the year. He has also had a fierce dinger problem in the bigs, although a 25.9% HR/FB suggests that at least some of that is noise.

To put it bluntly, Gaviglio's peripherals are not very good. FIP has him at a woeful 5.83 mark, and while xFIP is kinder, it still has him at 4.71 - a barely-acceptable-for-a-fifth-starter mark. It is easy, armed with this information, to point at Gaviglio and conclude that he's a fluke and will come crashing down to earth at a moment's notice. But while he indeed has a very thin margin of error, there's another part to his game that has given him success, at least for the moment.

Sam Gaviglio is a wizard.

Okay, not really, but he has posted a well above-average 81.4% LOB% this year. Gaviglio has also been very proficient at inducing ground balls: his 52.2% ground ball rate is second-best among Mariners with at least thirty innings pitched. While the early home run problem is worrying, the good news is that he has mostly limited the damage to solo shots - seven out of ten (!) dingers allowed. So far in 2017, Gaviglio has dug in with runners on base, holding hitters to just a .213/.283/.383 slash line with men on, as opposed to allowing a .258/.314/.536 line with the bases empty.

What has been key to Gaviglio's wizardry is the double play. Going to Saturday's game, Gaviglio has induced six double plays out of twenty opportunities - an excellent 30%. Five of those have been with a lone runner on first base, snuffing out potential rallies before they even begin. For a pitcher with a marginal repertoire, double plays are paramount to success, and Gaviglio has done a good job at inducing them.

So what can Gaviglio do to maximize this sorcery? For starters, he relies heavily on his sinker, throwing it an even 56% of the time. Beyond that, he has a slider that he likes to mix in every so often - especially against righties. He also flashes a curve and a changeup on occasion. Below is every sinker Gaviglio has thrown in 2017:

Gaviglio has done a very solid job of pitching right-handed hitters down and away with the sinker, generating plenty of soft and medium-hit ground balls. He's leaving the ball up against lefties more than I'd like, but is still getting the medium-hit ground balls he crucially needs for those double plays.

What I was surprised to find, however, is that Gaviglio is currently running a massive platoon split, with right-handed hitters posting a .362 wOBA against, including a healthy .266 ISO. How could this be? The ground balls are there, the 6.7% BB% versus righties isn't horrible...

Oh. Oh no.

Remember how I said Gaviglio likes to throw sliders against righties?

As shown, Gaviglio has been unable to consistently throw good strikes with his slider. He has managed a below-average 13.2% swinging strike-rate on the pitch, and when hitters do connect on it, they tend to square it up: batters are posting a 146 wRC+ and a .385 ISO against Gaviglio's slider. While he's still getting grounders with it (52.4% GB%), he's also allowing a lot of fly balls - nearly 40% of batted balls against. Coupled with a likely-to-regress 37.5% HR/FB on the pitch, and it's simply a recipe for disaster.

So the slider clearly isn't working for Gaviglio. Remember, though, that he also mixes in a curve and a change on occasion. With the caveat that we have only 67 pitches to look at, here are the results of Gaviglio's curveball:

Look at that! He likes the curve against lefties a little more, but Gaviglio has been able to throw it in the lower third of the strike zone against same-handed hitters with ease. He has yet to walk anybody on the pitch, and results-wise, it has been very effective - hitters as a whole are managing a -12 (!!!) wRC+ against.

Again, this is a very small sample we're working with here. 67 pitches is nothing - an efficient pitcher will often get through five innings on that amount. But there's a lot to like from the early results. For one, hitters have yet to regularly barrel it - their ISO against is a mere .063, or about the same mark that 2016 Ketel Marte posted. Second, while the curve has produced ground balls at an impressive 58.3% clip, Gaviglio has also used it to coax pop ups. Batters are running a sky-high 50% IFFB% against it, and while that almost certainly won't continue, it's something to keep an eye on.

His changeup is his fourth pitch, and it isn't a very good one. He pumps it in against lefties on occasion, but has simply left the ball up too often for it to be a viable out pitch. Gaviglio has only turned a changeup into a ground ball 26.7% of the time, and has given up three home runs off of it in just 59 pitches. It's not pretty, but below is where he has thrown the change this year:

Putting myself in Mel Stottlemyre Jr.'s shoes, my first instinct would be to tell Gaviglio to ditch the slider and focus more on his curveball. The curve is showing very, very early signs of being an effective pop-up and ground ball inducer, and the slider just hasn't been effective against same-handed hitters. The sinker is effective and is used the right amount, in my view, but the lack of a truly effective secondary pitch hurts.

Sam Gaviglio is likely a career depth starter or swingman. Mayyyybe if everything breaks right - especially if he develops his curveball - he can top out as a decent #4. The results have impressed, though, and while I'm sure many of us have severe doubts about their sustainability, Gaviglio deserves a solid chunk of credit for stabilizing the rotation and keeping the bats in almost every game he's pitched. After nearly every Dipoto-acquired depth piece either succumbed to injury or ineffectiveness, it turns out that one of the guys they already had has outpitched them all.

Thanks for the efforts, Sam. We have won the Ty Kelly trade.