I don't know. I think he's more consistent than guys like Nieto and Hertl. Granted those are young players, but if you put the big 4 forwards aside, I can't see how Sheppard has consistency issues.
The issue with Sheppard is that everybody is asking way too much from him.
He's been thrown around on the bottom 2 lines on the wing and center, playing with a lot of different players for as long as he's been in SJ. How is he supposed to find his game when you don't give him a chance? This team relies on the top 2 lines for offense, but sometimes you can see one of the bottom 2 lines stepping up. Sheppard is pretty much always part of that line.
The only part about this trade that I like is that it's probably the best for Sheppard himself. I wish him well in the Rangers, and I hope that they will give him more stability.