For the basics on Diamondback's SP Tyler Skaggs, check out Jason Hunt's piece from last season
What has his performance been like?
Tyler Skaggs rose to the top of the pitching prospect ranks with his impressive 2011 performance. He was highly regarded prior to that but his 198 K in 158 1/3 IP with a 2.96 ERA between High-A and AA got everyone's attention. This reminded many of Matt Moore's tremendous 2010 season in which he struck out over 200 in less than 150 IP with a 3.36 ERA at High-A. There are some similarities between Moore and Skaggs in that both are high strikeout LHP who can potentially be even more dominant if they can improve their command and control enough.
What is his current status?
Skaggs picked up right where he left off in his MLB stint last season and is currently struggling a bit. He had a 5.83 ERA with 21:13 K:BB and 6 HR allowed in 6 GS last August/September after being called up. Skaggs has a 6.21 ERA in 7 AAA starts this season. His FIP is just 3.17 and he's struck out more than a batter per inning. So what's the problem? He's been hit hard with a BABIP of .345 which indicates some bad luck. Also, his BB/9 of 3.58 is the highest he's ever had in the minors. In addition, the PCL is not exactly the easiest league to pitch in.
What can we expect moving forward?
The struggles in MLB combined with the struggles, at least with command, early on at AAA this season probably mean that Skaggs will spend most of the season at AAA fine-tuning his game. He could probably be called up right now and be a decent starter but with the Diamondbacks SP depth and Daniel Hudson a couple months away from returning from surgery there is no reason to rush him. I think the most likely scenario is that after spending the rest of the year at AAA with a possible September call-up we will see a better and more prepared Skaggs begin next year in the Diamondbacks rotation. While Matt Moore's upside is to be an ace, it's likely that Skaggs upside is to be a solid #2 SP while it's most likely he ends up as a strong #3. If he can get his walk rate down then we're looking at a guy who will likely produce around 175 K in 200 IP with an ERA in the 3.6-3.9 range and a 1.28-1.33 WHIP. There's certainly potential for more but that's what I'm expecting as of right now... for 2014.
I feel that it's worth mentioning that Tyler Skaggs is, in my eyes, the clear #1 call-up should the Diamondbacks need a SP. Many of you might be thinking about whether Randall Delgado would be the guy instead of Skaggs but Delgado is struggling even worse than Skaggs and it's not because of bad luck. If you see a Diamondbacks SP has been injured then I recommend adding Skaggs right away if you need SP help.