He still has his senses. Remember Anakin and Obi-Wan, able to sense everything that was going on in Padme's room? How can you possibly surprise people like that?
Besides, it's the long therm sensing that seems to have gone wrong with them, it seems, not their reflexes caused by brief glimpses of what is to come.
rubbish is a strong word. i agree the 98% of GL's options with boba would probably come off as crap. but depending on the rest of the script, it could be done in a way that would satisfy most fans, whether of mace or boba. we all assume we will see mace die and that will be a disappointment but after aotc i think boba will be the sentimental favorite to pull it off, which is possible with a little cunning and ingenuity.