Duncan, I disagree.
This is exactly the kind of acquisition that puts mid-market teams like the Royals into a hole.
It's the high price of mediocrity that kills in this league and the Royals most certainly just found an expensive chunk of mediocrity to plug into their rotation. His HR rates went up because he lost another .5 mph off his fastball. He's now sitting comfortably in that 'bleh' starter range at 91.5 mph. His slider, while once something of a wipeout pitch, has simply eaten his arm alive. The guy has spent the last 1,000 innings of his career throwing a slider for 1/3 of his pitches. In the process he's never really bothered to develop an adequate 3rd pitch and there's all of about 6 mph difference between his fastball and his changeup.
Maybe he levels out at the 4.00 ERA range, but the degradation of his stuff suggests that he could also just be shot. You have a finite number of bullets in the gun and 2-pitch pitchers that rely on sliders and fastball velocity have fewer still.
At best, the Royals had better view this guy as a turn and burn option. Get your year out of him and if it's worth a !@#$ (which is still unlikely, IMO), cast him off to some other poor soul that is willing to ignore the damage he's done to his arm over the last 1/2 decade.
If you can't draw a crowd, draw dicks on the wall.