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Here's what to watch for in Jon Gray's debut

Jon Gray makes his MLB debut tonight. Here is a guide on what to watch for.

Caitlin Rice

Today, my good friends, is Jon Gray day.

If finally happened. He is ready.

The most highly touted Colorado Rockies pitching prospect perhaps of all time will make his debut against the Seattle Mariners tonight at Coors Field.

This is a quick guide on what Gray is all about and what we should all be watching for this evening.

Pitch Types:


It is accurate but a bit of a misnomer to categorize Gray as a three-pitch guy. His fastball works as two, sometimes even three distinct pitches.

First, he throws the traditional straight fastball with little to no break. This pitch is most effective when he power-pitches.

He isn't afraid to work up and in with it:

Jon Gray, fastball, gif

The next two gifs come courtesy of our friend Hayden Kane in this piece at Rox Pile. The first is the fastball with tail, similar action to a two-seamer.

Jon Gray, fastball

And with sink:

Jon Gray, fastball, sinker, gif

Sometimes the fastball has natural tail and/or sink and sometimes he throws it that way on purpose. There is typically no drop-off in speed with the moving fastballs. In fact, if anything look for him to dial back (even to 91 or 92) on the straight ball on occasion in order to paint edges of the strike zone.

It is the case with Gray, like is is with so many, that he gets hurt when the fastball floats over the middle and upper parts of the plate. But make no mistake: He is a power pitcher not at all afraid to come up or in.


Gray's put-away pitch is his nasty, two-plane slider. With movement that often resembles a "slurve" Gray's slider breaks hard down and away from right handed hitters and while he can throw it a bit harder, it tends to sit in the mid 80s.

Gray's slider is what has allowed him to reach the heights of hype that he already has. It's been a plus pitch since day one and as such has been put on the back-burner for much of his minor league development in favoring of focusing on his change-up.

Slider to Will Nieves (Vine by Craig Goldstein:)

When he has it going, the fastball/slider combination looks like this:

Jon Gray, fastball, slider


The change is the pitch we should all have our eyes glued to this evening. I wrote two years ago that Gray was excited talking about his new offering as though "he had discovered it under the tree on Christmas morning."

Since then he has shown flashes of brilliance with the pitch but it has been inconsistent. When he buries it, it becomes devastating but when it hangs on him, he gets into real trouble and guys go back to just sitting on his fastball.

Change-up to Wil Myers (Vine by Craig Goldstein:)

Frequently asked questions:

Should I expect him to hit triple-digits?

No. It may happen at some point in his MLB career but I wouldn't expect it in his first game or two. Either way, it won't be a common occurrence if he does get there. He has an odd way of fluctuating between velocities. The only time I've seen him hit triple-digits personally was in Grand Junction when he threw a 102 mph fastball in the fifth inning. The rest of that game he sat on 95-96.

So it may show up, but it will be random.

Will he sit on 97-98?

No. Gray is not the typical power pitcher in that he can often sit in the low 90s with his fastball for the first few frames. If he comes out and doesn't top 93 mph in the first couple of innings, do not fret, do not adjust your television set. Gray prefers to get stronger with the fastball as the game goes on. Unless he is just amped up for his debut, I would imagine you won't see his best stuff until the third inning at the earliest.

Seriously is he a strikeout guy or a pitch to contact guy?

Jon Gray is now and has always been a strikeout pitcher. His wildly misunderstood, and self-driven, desire to improve at pitching to contact was never an effort to change who he is but rather to add another tool to his already impressive bag of tricks.

He will, especially when he is feeling it, do everything he can to miss bats, that's just the way he is programmed. This was seen in his most recent stretch of good starts that saw his K rates rocket up to over 12 per nine innings but also saw some drop in efficiency.

With Gray on an innings limit tonight (but oddly enough not a pitch limit) I think you will see him come out looking to strike out every batter he faces.

Does he have the killer instinct?

This remains to be seen. His performance in spring training suggests he relishes competition against the best. He was the first in a string of Rockies draftees to tell me that he views Coors Field as an exciting challenge and one he wants to prove he can conquer. He is one of those guys who will desperately search for a way to do something the second you tell him he can't do it.

But can he maintain a "bulldog" mentality at the MLB level for a consistent time period? Only time will tell on that one.