Scouting is just half of the job, and rumours about players United were linked with at least show that we're not shooting blindly, Sergi Roberto or Perisic for example are guys that have been playing good this season and United was trying to sign them to some extent.Probably a combination of all the factors that both of you mentioned. I would imagine the scouting's been a problem but it's hard to really discern how much at this club. There's no way to tell how much of the waste when it comes to transfers has come down to lack of proper scouting and how much of it has come down to Moyes/LVG/Mourinho not going with recommendations from scouts.
The problem is not only finding talent, is getting rid of all the players you have in the squad instead of hoarding them to see who works better through the season. The amount of depth this squad has is only comparable to the mediocrity of a lot of those players in those positions.
7 players can play as either CB or L/RB, but none of them has really shown United quality in a consistent basis (Bailly, Lindelof, Jones, Rojo, Smalling, Blind, Darmian).
8 players could "potentially" play as DM, but only Matic and an aging Carrick really would be good enough to play 50 games a season at top level
Pogba is the only player you would play 100% of the time in the midfield along those DM, then you have...
7 players fighting for the remaining 3 spots betweeb Pogba/DM and the ST (Herrera Fellaini, Mkhi, Mata, Martial, Lingard, Rashford)
Striker and GK are the only spots balanced with 2 solid options and players that can fill the role good if there's a catastrophe.
I look at this squad and I don't really get if this is a roster designed to fight for titles, or just the queue for tryouts in the X Factor EPL edition. You want to sign good players like Perisic or star players? Then you need to let go the dead wood in the team, if Mourinho had been coaching City for the last 2 seasons he probably wouldn't risk to let go in a couple windows players like Jovetic, Dzeko, Bony, Nasri, Zabaleta, Clichy, Sagna or Hart. They weren't really worse than Valencia, Young or Fellaini but like we say in our town "Let people leave before entering"