This is not a bug, it's designed this way.
See BB-Charles his post here
(104263.17);
The brief version is that it's surprisingly hard to write an AI that will determine the best way to use a timeout. Timeouts currently are called in order to do at least one of the following:
- Blunt the other team's momentum
- Rest tired players while keeping them in the game
- Advance the ball without the clock moving (late in the game)
- Draw up a play (late in the game)
Despite quite a number of tries at the problem, we have never managed to write an AI that does a good job of balancing all of these; typically the most "advanced" tries we've had at the problem result in the team running out of timeouts. As much as I'm a Vinny Del Negro fan, we've ended up writing an AI that leans heavily towards conserving timeouts to have as many as possible available at the end of the game, when star players get the most advantage out of getting rest during timeouts and when advancing the ball is at a premium. This also means that the team who is ahead very often will end up conserving all or nearly all of their timeouts until the end, then not using them.