In the interests of fair comment, a few bits of note I had first hand experience of:
We were in the group waiting for the first tram, having had an 8-10 man police escort for 5 of us from Barkers Pool, to the City Hall tram stop. The police encouraging us to board the tram, encouraged as many as possible on, before removing a few to free up space for other members of the force to accompany them. Supertram staff were on site, including obviously the drivers, but a rather optimistic ticket lady who was trying to take as many fares as possible. One of our group of 5 was trapped on this tram, the other 4 got off.
At this stage, another was approaching from behind and the police on site (who I asked personally) said they weren't sure whether or not there would be space on the second or if it would be full from the previous stops. At this stage, our group decided to go for a taxi instead to avoid the issue... only to then be told by other member of the force while we tried to cross the road, that we'd be okay and they were ensuring dedicated trams got us there in time. We then headed back to the stop and got on the second, slightly more comfortable tram.
The trams were held for a short while next to the city hall, I assumed this was to sort a clear run up West Street, no information was given and the opinion of the force from outside of Sheffield was "Don't know mate, we don't get told the finer details, we just have to go with the flow". I've also seen speculated that during this stoppage and a later one that there was a suspicion that it wasn't safe to move the tram so full -
that is merely speculation though.
This doesn't appear to be the delay alluded to above, that was much later and part of a series of stops/delays on the route.
All we were told on the day is that the sole reason for the stoppage is that someone on the first tram had pulled the stop cord and that it was their fault, not the fault of the police. For a while, with people getting antagonised, they refused to open the doors of the tram as we'd "soon be setting back off" - folk from the other tram were at this stage quite forcefully trying to get on our tram, with a police office having to get fairly aggressive with one who was trying to force the doors to get on (at least he wasn't refusing to!). Eventually, one of the police (not SYP) told the driver (without any further radio instructions) to open the door, at which point we made a hasty exit.
Further down the tracks at this stage, riot vans blocked the tracks just the other side of the entrance to Hillsborough Barracks... which is a strange reaction to a trams stop cord being pulled - remember, this was supposedly after the all clear, yet, before the Shoreham View video which shows the apparent reasoning that they were clearing passage.
The SWFC fans causing a threat absolutely had dispersed, because, down to quick thinking and luck, we avoided the police blockage and walked the route directly through Hillsborough corner and to the away end.
As we reached the turnstiles (having jogged/run - I got in just before Fleck's goal - after kickoff), they all seemed to be open, there were plenty of stewards and some police... I mentioned the problems to the steward that searched me... at that stage they had plenty of staff around to deal with what was about to come.
This was mooted by a member of the force before the away fixture, and there was indeed some positive dialogue and feedback given... The problem is, that's not really a solution in avoiding the happening we're talking about, the explanation is they had to make split second decisions on the day... there's no predicting that... it's an issue of communication and mistrust in the reasoning given.