I'll refrain from pointing out the strong political biases your sources because I did cite the NYT, but I wish to note their use of tone arguments to highlight waste. $22M a year spent on teachers awaiting arbitration sure sounds like a lot as a number out of context. Take a minute to note that they have close to a $20B[1] yearly operating budget, putting the cost at roughly 0.11% of their spending.

I don't wish to make the argument that this makes the spending or this practice ideal, but rather than in scale of the NYC DOE it does not appear to be as large of a leakage as the press might like to make it seem.

[1] http://schools.nyc.gov/Aboutus/Funding/overview/default.htm

The other way to figure it is that ~220 out of 75k teachers affected suggests a waste factor of 0.3%. (which agrees with your number if teacher salaries are about 1/3rd of the operating budget.) It's still substantial because in absolute terms $22M is a lot of money and it's all waste - the only sane policy would be to just fire these people or put them on unpaid suspension.

Nonetheless if we are to believe the official figures, they claim the number of rubber-roomers has declined from ~700 to ~200. Which isn't "dismantled" but is certainly "reduced"; it does seem like some progress is being made.