Stephen Strasburg’s AFL Surprise

Stephen Strasburg made an impressive start Monday in the Arizona Fall League. Working into the fifth inning, the top pick of the 2009 draft showcased his elite stuff. Despite the scouting on the Nationals phenom, eyebrows were raised by Strasburg’s velocity.

The AFL has PITCHf/x installed in both Peoria (home of two clubs) and Surprise, leaving Mesa and Phoenix in the stone ages. Strasburg’s visit to Surprise was just his second start in front of the PITCHf/x cameras and keen observers noted an increase in his already impressive velocity. On Oct. 22, Strasburg threw in Peoria, where he topped out just under the century mark. In Surprise, Strasburg broke 101 once, and threw 12 other pitches over 100 mph.

One benefit of the AFL is the sheer volume of pitchers used in each game. Of the pitchers appearing Monday in Surprise seven, including Strasburg, had also made an appearance in Peoria. The other six: Josh Wilkie, Drew Storen, Tanner Scheppers, Jeff Mandel, Scott Gorgen and Danny Gutierrez. Wilkie happened to pitch, along with Strasburg, in Peoria on Oct. 22.

Trust but verify

Isolating four-seam fastballs, let’s start with a comparison of Strasburg and Wilkie in Surprise on Nov. 2 (red) and Peoria on Oct. 22 (blue) (click images to enlarge):





Two more pitched in Peoria on Oct. 21, so let’s throw their fastballs into the mix





Future Nationals closer Storen worked in Peoria on Oct. 19. He was faster in Surprise, too.


I can’t say the PITCHf/x system was hot in Surprise, only the Washington blue-chippers.

Getting used to Strasburg

Stephen Strasburg is proving to be everything he was hyped to be. He threw 101 and sat at 98. He threw sinkers in the upper 90s. His change-up was 90 mph. His curveball had snapping movement and was thrown as hard as most sliders. He’s a nightmare for hitters already.

Strasburg is also young and developing. All pitchers have some game-to-game difference in stuff—speed, movement and selection. Surprise may have been the scene of an unusually strong outing. It may be normal for him someday. Whatever it was, the speed wasn’t an illusion.

References & Resources
PITCHf/x data from MLBAM
Pitch classifications by the author
Inspiration came via Twitter (@projectprospect and @bigmike05)

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Peter Jensen
14 years ago

Harry – Any comments about anything in the pitch f/x information that might be causing Strasburg’s lopsided reverse splits with righthanded batters hitting .357 against him with 3 home runs and left handers hitting .138 with 0 home runs?  I’ve tried to program my computer with a small sample size alert button but haven’t finished it yet, but this is where I would use it.

Jim C
14 years ago

As a native of Washington DC who grew up with a lot of bad Senators teams, and having been appalled at the hideous Nats of the last few years, I can only hope that Strasburg lives up to his potential, and that Drew Storen becomes a reliable closer.

14 years ago

Throwing 100mph is impressive no doubt.
But should people be concerned with his sky
high 6.97 ERA as of Monday??

Drew Storen and Mike Leake look like they
are executing pitches better than Strausberg

am I sensing too much hype??

Harry Pavlidis
14 years ago

Jason – the ERA is of no concern after such a short stint. Besides, the AFL is a hitters league (like none other) and Strasburg had one bad day.

The hype I’m sensing on Strasburg seems just about right. Folks realize he’s not polished, unproven etc. But his stuff is as advertised.

I’m due for a closer look at Leake and Minor, amongst others, too.

14 years ago

It’s funny my Parents-in-law live in Surprise literally 5 minutes from the stadium, and my father in law doesn’t care anything about baseball. Just kinda funny to me because if I lived there I would have unquestionably been at the game, front row taking it all in.  Makes me feel almost jealous, but he doesn’t care anyway, so is that really jealousy if he doesn’t give a sh*t? I’m confused…

Geoff Young
14 years ago

Speaking as someone who saw Strasburg pitch several times when he was at SDSU, the only people I’ve heard suggest there might be too much hype are those that haven’t watched him. He may or may not pan out (things happen), but his stuff is electric.

Harry Jebsen
14 years ago

I saw him at Peoria the previous time out and he was not impressive giving up long taters and with little control

Adam Foster
14 years ago

It’s one thing to say that the Surprise PitchFX system isn’t hot in comparison to the one in Peoria. It’s another to declare that Strasburg sits at 98 based off this data.

If you look into the manor in which PitchFX data is gathered in contrast to radar guns, there’s a strong possibility that the two are not going to be in agreement.

Taking a scale that has been calibrated over decades of radar gun data and applying it to a piece of technology that reads differently is a risky venture.

Let’s not jump to conclusions. While PitchFX appears to be a better solution to reading velocity than radar guns in the long run, work needs to be done on the application of the traditional radar gun velocity scale in contrast to PitchFX. There’s clearly a void here. A lot of people are trusting data without really understanding what they’re looking at.

Todd boss
14 years ago

For those who are not following the league and all of Strasburg’s starts (poster Jason above), he has basically had three stellar outings and one incredibly bad outing, giving up 7 runs in 2 innings to inflate the numbers.

The post-game analysis in the “bad” game seemed to indicate he was leaving lots of pitches up.  No matter how fast you throw, talented hitters will catch up and knock you around.  In the other three games he’s kept the ball down more and worked on specific pitches in each game.

Remember AFL isn’t spring training; he’s not trying to win a spot in our rotation next year.  He’s there to get some innings, put some experience on his arm, and work on perfecting his non-100mph pitches.

Here’s to Strasburg in Nationals Stadium in 2010!

14 years ago

Thanks. I’m well aware of the accolades at SDSU.
I’m just worried that people see 100mph and
assume he’s the next Nolan ryan. I was just
following him (along with a highly touted Moustakas)
and stat-wise, granted, a short AZFL season, they seem to
be off to a slow start. I’m not downplaying Strausbergs
capability and skills, simply wondered that now
that he’s pitching to some of the best minor
league bats teams have to offer, he’s not as
good as we all thought. That’s all.

Harry Pavlidis
14 years ago

Adam – since you’re not specific enough about the “manor” data is collected, or of my own lack of understanding, so I’ll try this generic response.

Radar guns seem to pick up the pitch around 40-50 feet from the plate. The data I present is from 55 feet out. It will almost be always be hotter than the gun, all else being equal.

Whether or not your gun agrees, Strasburg sat on 98 on Monday based on a very precise and accurate estimate of the path of his pitches. Your miles per hour may vary.

Adam Foster
14 years ago

Strasburg’s last outing is a good example of why radar guns and PitchFX need to be looked at as different flavors of data. Readings are being taken from different points with both pieces of equipment.

We should probably compare the average AFL fastball with the average MLB fastball, too. Isn’t there a chance that both PitchFX systems could be reading “hot” in the AFL?

Jim C
14 years ago

As a Nats fan, I sure hope he is NOT the next Nolan Ryan; a pitcher who holds the walks record by the same margin he holds the strikeout record, and whose career W-L is no better than the mediocre teams for which he played most of his career. I hope he is the next Tom Seaver.

Geoff Young
14 years ago

@Jason: Cool. To be clear, my comments weren’t addressed specifically to you. I’ve just heard the hype angle played up by many people who haven’t seen him and it always puzzles me.

Whether he is as good as we all thought… that depends on how good we all thought he was. I thought (and still think) he’s going to be pretty darned good, health permitting.