This is how I understand it:
LTIR gives teams flexibility to go over the cap, but not to it. The salary cap of Robidas, Horton and Lupul still applied to our cap hit this season, and in essence, we got no cap releif. The Leafs did not use any of our LTIR cap space this season which you can tell when we were ~100K under the cap at seasons end... if we used LTIR space, we'd be at 0. LTIR gave the leafs ability to ADD cap (up to ~12 million), but they didn't utilize it at the TDL. (A missed opportunity IMO, maybe we were planning on adding but deal(s) fell through).
Furthurmore, LTIR does not benefit the club when you take ELC bonuses into account. By placing Horton, Robidas and Lupul off LTIR, and sending them all to the AHL, we would have 2.85 million (950K each). This could have contributed to cap savings which COULD HAVE been used to the accumulated ELC bonuses for Matthews/Nylander/Marner.
Now, nearly the entire bonuses will go to our cap hit next season.
At the end of the day, because we didn't acquire any large contract(s), we would have been better off NOT having Lupul et al. on LTIR as it would have lower our commitment to rookie bonuses for next season.
Does this make sense?