Over the last year or so I have studied and written quite a bit on the topic of timeouts. You can read all of the posts I have written (in English and in Polish) by following this link.
The upshot of all of the research I have done with Ben Raymond is that timeouts do not seem to work in the way that we (coaches, fans, administrators) like to think that they do, that is they have no impact on the game.
An American researcher, studying USA college matches and looking at over 5,000 timeouts found eerily similar results. They are summarised in the infogram below.
It is worth noting that at his AVCA Convention presentation (https://s3.amazonaws.com/avca-audio/2016_convention/Timeouts+and+Momentum) Ho suggested that timeouts ‘could’ serve to reset a team back to their norm. If so, then you would see post-timeout sideout rates similar to general sideout rates as the data show. I think to test that suggestion you’d have to do something like a randomized trial – say when you think it’s time to call timeout, flip a coin as to whether you will or not. Hard to imagine many coaches going for that, though. 🙂