It's worth noting that if you subtract the awfulness called Brad Hennessey the Giants bullpen ERA would shrink to 2.92 which would be good for third best in the NL so far this year. It's hard to figure just what the story is with him after such a good 2007.
It's probably not a shredded arm even after he saw action in 69 games last season since he pitched less than an inning a game on average. But given that his poor performance so far has moved him to back of the bullpen, the big league club isn't the place for him to work out the problem whatever it is.
Look for Hennessey to be the odd man out and Fresno-bound once Noah Lowry is ready to be activated. Who takes his place is a matter of conjecture but most speculation is that Kevin Correia would be out of the rotation and into the bullpen.
Fair enough. But it would be a terrible oversight to fail to segue from Hennessey to Heresy...
If Lowry is sound and ready to resume starting when he's activated then the right call is to put Barry Zito into the pen and give Correia more of a chance as a starter. At least Correia has a small potential upside which Zito would not appear to have if things go as they have.
Sending Zito to AAA to work on things is fairly pointless as even with bad stuff he'd still dominate most hitters down on the farm. But what he can do while still with the big club is one thing (and probably the only thing) that could salvage his career and some value from the roughly $100 million the Giants still owe him.
The point has been made that Zito isn't a natural thrower and got as far as he did on mimicry without the right physique to make a long and successful career very likely. His ability to study and master technique are where his residual value lies; certainly not in his 84-mph fastball...
Send Zito to the pen and have him work on a knuckleball.
He's not fooling anyone as a conventional pitcher and with an ERA close to 6.00 he's not even a candidate for a plus-cash trade. Add in the appeal of having a knuckleballer to break up a hard-throwing rotation of Lincecum, Cain and Sanchez and there's a case to be made for at least trying it. Otherwise it's 4+ years of wasted money, but if he can get some proficiency with a knuckleball he at least retains some value to the club and maybe can be moved later.