The ongoing situation was fairly obvious for me. Welbeck had been narked by Moyes' implication in December 2013 that he should train as hard as Rooney, the manager at that point was still going through his very own ongoing process of fellating Wayne Rooney. Welbeck publicly came out and rebuked what Moyes had indicated.
Welbeck then found himself playing as central striker for a period of time and delivered a healthy return. He was then, along with Januzaj, dropped as soon as Rooney and Van Persie returned. He would only play on the wings when Moyes was indirectly instructed to do so from Gary Neville's seat in the Sky studio. He had a poor relationship with the manager, was worried about his future and was setting himself up for a move in the summer. I have no issue with that. This was reported heavily by our whole beat, as well as chief football writers.
Van Gaal comes in, Welbeck is clearly happy to stay under a new, exciting manager that he may believe will opt for a 433, whereby he'll get plenty of game time. Welbeck conducted an interview just before the World Cup in which he stated he was looking forward to life under Van Gaal.
Over the course of the summer Van Gaal decides that Rooney and Van Persie are his main men and if Daniel Taylor is to be believed the Club has been on the lookout for another striker with "dynamism" for 12 months now. James Wilson's rise in reputation throws a spanner in the works and Welbeck is ultimately informed that he won't get many games under the new regime. Welbeck then decides, for the good of his club and national team career, that he'll be better served leaving the club and getting game time elsewhere. Understandly, he moves to the best club possible. All parties, for the most part, seem satisfied.
If you've followed the media reports from creditable people within the industry - and they are directly sourced by Welbeck's very talkative camp - then I think this is a likely scenario. Basically, nobody has done much wrong here and the accusations flying around are mostly bollocks.