Hellickson's changeup makes him interesting trade target

So far, the top starters moved before the Trade Deadline have been Andrew Cashner and Drew Pomeranz, who are good but not stars, and in that context, suddenly that makes an available pitcher like Jeremy Hellickson perhaps more interesting than you'd think.
Over the course of his career, Hellickson been about the definition of average. Sure, he once looked to be more than that. As a Minor Leaguer in 2011, Hellickson was ranked as the No. 2 prospect by MLB.com. He was arguably the most hyped pitching prospect in baseball, sandwiched between Teheran and Aroldis Chapman, and then he started off his career with 400 innings of a 3.00 ERA.
• FanGraphs' Jeff Sullivan wonders if the Royals should trade Danny Duffy
So that was a good start, but then the performance took a step back, and then the elbow surgery came, and Hellickson became an overlooked name as quickly as he'd become an intriguing one.
The Phillies are reportedly asking for a team's top-five prospect in order to obtain Hellickson; otherwise, they're comfortable extending to him what could be a $16.7 million qualifying offer. Which, of course that's what the Phills are asking -- no harm in talking up your own guy. The question is: how crazy is it, really? Or, more specifically, how interesting is Hellickson, really?

The basics: Hellickson's 29, earning $7 million in his final year of arbitration, and will soon be a free agent. The reason the Phillies are asking for him what they're asking: the former top prospect is currently running a career-best FIP-, a career-best xFIP-, and career bests in strikeout rate, walk rate, and swinging-strike rate. (All of that is not counting his 36-inning debut in 2010.) As far as full seasons go, Hellickson's never looked better.
Maybe that speaks more to Hellickson's past than to his present. The FIP is still 4.17. The ERA is 3.65. They're good numbers, and certainly better, but it's not like he's suddenly looking like a front-of-the-rotation starter, the kind of guy you look forward to starting a playoff game. Working in the Phillies' favor is that Hellickson, lately, has pitched like the guy you look forward to starting the playoff game. Over his last seven starts, spanning 45 innings, the ERA is 2.20 and his FIP 3.27. Of course the Phills should be asking a higher return than we might expect -- he looks better now than he's looked in some years. But could there be more?
Hellickson's two biggest issues have always been the same: lefties and the long ball. I want to focus on the former. Because, see, there's one easily identifiable reason not only for Hellickson's improvements over the course of the season but, more specifically, over the last month, and it relates directly to his issues with left-handed batters. Over the last month, Hellickson's ramped up the usage of his changeup relative to earlier in the season, a shift that's been met with great success. Which makes sense, because he's had one of the very best changeups in baseball this season.
The following image shows whiffs per swing. I don't believe it needs much more explaining:

That's insane. Let's work our way up the top-five in changeup whiff rates this season. In fifth is Marco Estrada, and you can read all about his changeup. In fourth is Michael Fulmer, and you can truly read all about his changeup. In third and second are Noah Syndergaard and Stephen Strasburg, and you already know about them. But none of the four have come close to touching Hellickson when it comes to making batters look silly with the change.
Just ask Miguel Cabrera:
Gif: Miguel Cabrera gives thumbs up to strikeout pitch (slo-mo)
FanGraphs' run-value leaderboard's got Hellickson's change as baseball's sixth-most valuable this season. Even on a per-pitch basis, it still ranks among the elite. It's getting more arm-side run than it used to, Hellickson's been working to get more drop on the pitch every year since he's been in the league, and that extra movement's allowing him to consistently spot it lower in the zone. Hellickson's changeup, as it stands, is better now than it's ever been.
So, Hellickson must be solving those lefties, right? The lefties were always half the problem, and now he is working with one of the league's most truly devastating changeups. Everyone knows a good changeup is the key to retiring opposite-handed batters!
Except, well:
Hellickson vs. left-handed batters
Career: .323 wOBA allowed, 4.69 FIP
2016: .330 wOBA allowed, 5.29 FIP
It's bizarre. It doesn't seem like it shouldn't be happening, but it is. Despite the strides Hellickson has made to turn his changeup into one of baseball's best, he still can't figure out lefties.
And then, more bizarre: Hellickson started throwing a cutter this year, but he's throwing it almost exclusively to lefties, which is counterintuitive. Moreso, when you consider they've slugged .724 against it. The four-seamer's just never been great, which is still the crux of the issue. And then, despite all the progress Hellickson has made with the pitch, he's actually throwing the changeup to lefties less often than in the past. I'm not inside Hellickson's head or his catchers, so I can't wager a guess as to what's been behind the pitch selection. I can say it's a head-scratcher.
On the one hand, Hellickson is the same as he's ever been. He's still giving up the long ball far too often, he's still getting killed by lefties -- and, even in a career year, he doesn't look like much more than a league-average starter. Maybe a bit better than that. On the other, even six years after his top-20 placing on Baseball America's Top 100 list, there looks to be some potential left still. Hellickson still has the fascinating curveball that gets more spin than anyone. And now, he's crafted his change to look like one of the game's best, which would seem like the key to solving the lefties. It just hasn't yet been used that way. It sure seems like Hellickson could just be one more tweak away. So the story goes.
A version of this article first appeared at FanGraphs.com. This story was not subject to the approval of Major League Baseball or its clubs.