Again, people are welcome to their opinion but you're talking about a 19 year old where as Edwards was 2 years older. His stuff from what I've read(not pretending I'm a scout here) isn't even that bad. You're talking a fastball in the 90-94 range that he can put where ever the hell he wants to go along with an above average curve and he's also got a change up that many scouts feel is his best pitch. If you look at pitch f/x data of pitchers with similar offerings you see guys like the following
Cole Hammels - fastball with 91.0 mph average, with a 2.06 Val/C change up and an average curve and nothing else spectacular.
Kris Medlen - fastball with 89.7 mph average, with a 2.09 Val/C change up as his best offering. He's got an ok curve at 0.66 Val/C but it's not dominating
Jered Weaver - fastball with 89.1 mph average with two decent offerings in a curve and a change up at 1.30 and 1.28 Val/C respectively
James Shields - fastball with a 91.3 mph average with two decent offerings in a curve and a change up at 0.77 and 1.32 Val/C respectively
Anibal Sanchez - fastball with a 91.7 mph average with two decent offerings in a slider and a change up at 0.68 and 1.18 Val/C respectively
Cliff Lee - fastball with a 90.6 mph average with two ok offereings in a curve and a change up at 0.61 and 0.57 Val/C respectively. Lee's likely a good comparison because his control makes his fastball his best pitch at 1.20.
With the exception of Lee, none of those guys has been a top 10 starter but they've all been low end 1's/high end 2's. And at the end of the day you can have the greatest stuff ever but if you can't locate you it does you no good. Take Aaron Sanchez for example. He's supposedly got 3 plus to plus-plus offerings. he also walks a crap ton of batters. What did he do in A ball as a 20 year old? 9.66 k/9 5.08 bb/9 with 2.49/3.57 ERA/FIP.
If you look at the top 30 pitchers in bb/9 since 2010 with a minimum of 500 IP you're talking about the following players Cliff Lee, Carl Pavano, Brandon McCarthy, Bartolo Colon, Doug Fister, Dan Haren, Roy Halladay, Jordan Zimmermann, Adam Wainwright, Kyle Lohse, Bronson Arroyo, Joe Blanton, Hiroki Kuroda, Mark Buehrle, Ricky Nolasco, Rick Porcello, Jered Weaver, Felix Hernandez, Zack Greinke, Cole Hamels, Chris Sale, David Price, Mike Leake, Madison Bumgarner, Phil Hughes, James Shields, Clayton Kershaw, Tim Hudson, Stephen Strasburg, and Jake Peavy with Peavy having the lowest at 2.39. The worst players on that list are Leake, Blanton and Pavano. The rest all have roughly 10 WAR or higher which puts them at roughly a 2.25 or higher WAR/season.
The real question becomes just how much k potential is there. If he's above 7.5 k/9 in the majors he's going to be a top of the rotation pitcher. Of the players with 2.4 bb/9 or lower and 8 k/9 or higher you're talking about Felix Hernandez, Clayton Kershaw, Cliff Lee, David Price, Adam Wainwright, Cole Hamels, Zack Greinke, James Shields, Chris Sale, Madison Bumgarner, Stephen Strasburg, Jake Peavy, Jered Weaver, and Dan Haren.
So call me crazy but I'm more than willing to buy into someone like Tseng than I am to buy into someone like Sanchez with his "amazing" stuff. Even if he's not much of a K pitcher you have guys like Fister who has been extremely productive the past 4.5 years at 16.4 WAR(3.64 WAR/season).
