Some people believe there is no way Wang is healthy. Michael Kay even comes up with his own take on his radio show: Wang has a bad shoulder. Others believe Wang's problem comes from bad mechanics.
As for now, I take Wang's words. Wang is not a 40 years old pitcher who is at the end of career. There is no point to pitch through injury, especially at the beginning of season. As my previous post points out, I believe what Bruney said. Because Wang hasn't trust his right foot or hasn't build up strength of his right foot completely, it leads to his bad delivery, terrible control and horrible command.
Because of long layoff, Wang's mechanics is not consistent and is difficult to repeat and regain. As for Wang's velocity, I see 92mph sinker from Wang with good movement from Wang during his last start against Indians. A lot of fans always like to add few mph when they describe how hard a pitcher on their team throws. Based on what I hear from Wang, Wang's sinker is around 91-93 while his four seamer will top at 94 at times. I don't think Wang loses 5mph on his sinker(95mph to 90). The way a lot of people claim.
Keep in mind three things. First of all, terrible delivery also can lead to drop of velocity. Secondly, Wang may hasn't built up his arm strength due to long layoff. Thirdly, Wang's velocity usually is up when the season goes on.
Even if Wang loses few mph on his sinker, he still will be a above average pitcher or at least average, serviceable pitcher if he gets his command, control and movement back on his pitches(sinker,four-seamer, sliders).
The only concern I have is Wang's bad mechanics may lead to arm problem later on.
P.S Based on interviews Wang have with Taiwanese media, Wang actually feels he starts getting his sinker back the last game against Indians. During the whole spring training, Wang has two concerns. First of all, he hasn't gotten his velocity all the way back yet. Secondly, he hasn't threw his sinker well yet. He is glad he starts getting the feel of his sinker. In his opinion, the movement and location is much more important than velocity.