Before I break a promise, let me see if I understand the consequences.

Had to recruit 10, and to balance my roster, I used two start promises on 1 year senior transfers.  Will WE be the only category that drops if I do not continue to start them?

Their cores are only high marginal, and after 5 games the freshman coming off the bench are better.  If their WE is all that drops, I will shake up things and start the young guns!  If their cores will also drop, they will start at least till the second semester starts.

Also, and YMMV, I did this (promised a start to a senior transfer and did not start him) and he never said a peep, never dropped, smiled off the bench,. worked hard in practice and even washed my car, so maybe nothing will happen. At worst, as ars said, I believe WE will be only drop and yes, your rep would take a hit, but those things happen...mostly affects ability to get new jobs, so if you are sticking around a while it doesn't really matter much.

I wonder if your reputation effects either how likely recruits are to accept your promises, or how much effect they have?  Would seem plausible.

You could also keep alternating them in and out of the starting lineup all season (odd and even starts) until the conference tourny. I did the same thing a few seasons back (promised multiple starts) and by doing the revolving door, they stayed satisfied.