Deck 72 and travelling 28,000 LY in 12 hours WITHOUT BS.
*waits patiently*
The 'Deck 72' is a problem I don't think we can conceivably explain, unless the designations meant something else besides actual decks (which is doubtful).
However, travelling through 28 000 Ly's in 12 hours is more or less easily explainable.
If you recall, in Star Trek III (the search for Spock), the USS Excelsior was outfitted with a Transwarp drive.
It is highly likely that the drive in question really resulted in massive increase in speeds, which subsequently found its way into the Enterprise-A (and possibly that Klingon BOP might have been part of covert operations that got an enhanced drive as well), but might have been later on suppressed by someone due to a number of concerns... such as venturing into parts of the galaxy, occupied by potentially dangerous species like the Borg that the Federation (and their neighbours) in the 23rd century would not have been necessarily prepared for. The Klingons were more or less by ST:V in a state of neutrality with the Federation (as we've seen in an explanation that the attack on the Enterprise was not sanctioned by the Klingon government - plus, the crew seemed to have 'welcomed' the Klingon crew aboard - and both sides seemed cordial/tolerant of each other there).
I would imagine early experimentation with TW would have allowed ships venturing deeper outside Federation space until they rescued El-Aurian refugees who fled the Borg and reported this to Starfleet.
The more technical minded minds of the El-Aurian refugees were able to explain something of the Borg and how advanced they were with adaptation to unknown technology and possible assimilation (which would explain the Hansens knowledge on the subject when they took Annika to look for the Borg in roughly the year 2355 - mid 24th century).
This might also explain why the Federation encompassed 8000 Ly's by the 24th century - because I certainly cannot see the Federation effectively doing so with slow Warp travel.
And besides, Warp 9.9 was stated to be 4 billion miles per second (21 473 times speed of light) on Voyager (and sometime after/before that, Kim also mentioned 'travelling at a relative velocity of 2 billion miles per second' to rescue Chakotay from the Kazon using Transporters while in Warp on a stationary target)... plus, if I'm not mistaken, every incremental increase past Warp 9.9 would result in exponential increase in speed, so 9.975 (which was mentioned to be the ship's top cruising speed - indicating a velocity at which a ship could move indefinitely without needing to stop for long periods of time) would allow Voyager to get back to the Federation in just over 6 days... but the trick is, we never saw Voyager at these speeds.
At most, the ship was sustaining Warp 6 to 8 mostly, on some occasions increasing to Warp 9, and rarely to 9.9 (because oddly, enough, passing 9.5 or 9.9, seemed to have resulted in the ship shaking itself apart).
I suspect the reason behind why the ship travelled at slow speeds could be attributed to their original transport to the Delta Quadrant by the Caretaker which severely damaged the ship and Warp drive, possibly on a subatomic level where repairs couldn't be properly executed without access to a specialized spacedock for Intrepid class ships (none of the drydocks they used in alien space would be suitable for those tasks apart from general maintenance, repairs and usually restocking - deep level repairs might require specialized facilities, and we've seen that most advanced alien species were reluctant to offer more than basic help - as for the Q and him repairing damage to Voyager caused by Junior - probably to the level the ship was before Junior forced it into combat... and besides, Q might have vested interest in keeping Voyager in the DQ, allowing events to unfold as they should).
Indeed, the ship experienced power problems early on, and well into season 2 and 3 while searching for materials/minerals which the crew could use to repair the Warp nacelles due to extensive combat damage (and we've seen they never got enough of these materials for the most part).
Of course, none of this was mentioned on-screen, but it does mesh relatively well.
Sisko saying stuff about the Dominion could easily be in reference to Domnion's slow Warp drive in general.
While Picard's mention of the Barzan wormhole and the distance it would entail travelling at Warp 9 (not 9.9 or faster than that) could be explained that past Warp 9, speeds start to increase in a large capacity, with exponential increase beginning after 9.9
This could also explain how ships were able to reach/cross through some regions of space in a short span of time - by pushing their engines to levels they weren't usually rated for... and the only class in the fleet that should have been able to sustain 9.975 indefinitely, well, Voyager disappeared and got severely damaged in the process, while the Belerophon would likely be limited in fleet actions to the slowest ship so they can all engage in numbers.