I think - and I've been guilty of this as well - their first team is so good that there's a lot of ignorance about their strength in depth. Take Modric and Bale out of that team and they're nowhere near as scary. I'd love them to come third, but in reality I think they'll have to hold off a late surge from Chelsea for fourth.
It's not just the quality of the players but the tactics being used. For example when you look at your squad, you have a few world beaters, and then a smattering of decent players. Tottenham's squad could largely be judged as the same, and outside of Rooney I think man for man, I'd pretty much take their XI over United's. They have a fantastic midfield.
Harry may be able to get players working hard for him with the creative freedom and encouragement to express themselves that he affords their players, but its clear from the intensity and doggedness that United play with (and the results) that you need solid tactics and training to keep those players who aren't world beaters working above their level and adding to the sum of the team.
Redknapp may be laissez faire to his own credit when it comes to players with immense talent like VdV, Bale and Modric, but perhaps its to his detriment with players like Sandro, Livermore, Dawson, Krancjar, Walker, etc.