Why can't he be Paul's backup? What if we don't go to an entire 2nd unit at once and leave in either Paul or Ray with him?
That sort of works, but it can't be when Rondo is in the game.
Tony Allen was most often used in a House/TA/RA or House/TA/PP configuration and I think Daniels could be used similarly, so he wouldn't play as much when Rondo is in the game. I could see the substitution pattern being something like:
Out Ray Allen, In Daniels - Rondo/Daniels/Pierce
Out Rondo, In House - House/Daniels/Pierce
Out Pierce, In Backup PG - PG/House/Daniels (a fourth wing could be employed for a House/Daniels/wing lineup instead)
Out PG (or House), in Ray - House/Daniels/Allen
Out Daniels and House, in Ray and Rondo - Rondo/Allen/Pierce
Sometimes Pierce will come out first, depending on matchups and fouls, but I could see Daniels and perhaps a fourth wing split 10-12 minutes in the middle of each half where one starting wing sits out the first part and the other sits out the later part, with a short 2-3 minute run where both Ray Allen and Paul Pierce sit. If Pierce and Allen sit for seven minutes each half, that means they average 34 minutes. Pierce and Allen each sitting for six minutes that overlap for 2-3 minutes each half would probably get them to the 35mpg that would be a tolerable load, once you factor in games where they sit more due to foul trouble or blowouts.
Then again, Doc tends to annoy people in this forum with substitution patterns that don't make sense.