I have an opinion on this as a Physio (only an opinion)
I think the warm time needs to be looked at and in sport it is a tricky balance as sports science, medics, physio and coached all have different agenda.
coaches want to go through everything before a game, but actually for me it is far too late to be practising line out lifts etc in the warm up IF it is practising. If it is 'warming up' the muscles to do that then yes but you would never warm up at full intensity (e.g lifting a player).
the warm up should be short and sharp and more focus on being mentally ready to play.
workload - this needs to be looked at across the whole week and season also. how much are we asking players to do in the week? I think pre season is for fitness and after that it is recovery and maintaining sharpness and tactics. otherwise we are overloading them and that is when niggles happen. A coach getting the forwards to work on scrummaging between games is almost asking them to play an extra game between games!
I was going to say something, but then a physio adds their bit and leaves me with nothing.
I will add however that a bit of tackling and a bit of roughing up before a game always helps me be better prepared mentally.
I wasn't suggesting that the warm up explained our defensive mess but always wondered why we often start slower than our opponents in general. Newcastle being an obvious exception.
What I'd like to see is when the team comes off after warming-up, that they run down the CENTRE of the pitch, towards the terrace - we give them a rousing cheer as it is, but I think 'owning' the pitch and running down the centre, rather than coming off at a diagonal, almost half-heartedly, would give a better message of intent to the opposition, and encourage our team that we are with them from the off.