I do think they lose it a little, or at least they seem more prone to no balls and wides if tired.Fatigue is something that would be cool if it could be improved upon. Currently it seems quicks just lose a bit too much pace and carry but that's about it. I'd prefer if they lost accuracy as well.
I found that pace bowlers need about 80+ in stamina in order to get a spell of say 6 overs. Although too much and they seem to be able to bowl 10 over spells. Fast bowlers lose it quicker too. I think it's a symptom of most the attributes appearing to be done using the overall (pressing +10 from a start of 0) so they end up about the same. Unfortunately the physical stuff, like strength, speed, agility are sufficient down in 40-60 range.