The West Brom match was one game. I agree Kagawa was looking especially dangerous that game and shouldn't have been taken out. That was Januzaj's 2nd match with a good amount of minutes and his first match where United were losing. He looked shaky because of how nervous he was. He was so nervous he even miscontrolled a throw in that match. Once he settled in though he looked dangerous going past players for fun and almost scoring in that match. I also agree that Kagawa was unfairly treated by Moyes and being dropped for the Chelsea match was an example of this. That still doesn't mean he was better than Januzaj last season or that he had a great season. Kagawa would be the first one to tell you he wasn't up to his high standards and yes Moyes takes a large part of the blame for failing to get the team to play modern football.
I also disagree that the team looked more fluid under him than Mata. Maybe you're thinking of Rooney and I would agree that I prefer Kagawa behind the striker than Rooney despite Rooney's end product. Rooney tends to look to the right wing too often, has games where his touch deserts him, and sometimes either drops too deep or occupies the striker's area too often. Mata though? Mata does what Kagawa does while also having more end product.
And how exactly does Januzaj not link the midfield better than Lingard in the #10 position? What proof do you have when you haven't seen Lingard in the PL? Januzaj did a good job doing that for the reserves. As he becomes more experienced he will learn to operate in the central areas much better than he was at 18 years of age.
It honestly feels like I'm being too harsh on Kagawa, but I'm really not. I'm a big fan of his, but I don't like how some fans act like he's flawless.
Here we go again quoting stats yet forgetting assists stat in particular, depends on the player at the receiving end. How people forgot Kagawa's sublime passes and crosses that were missed last season is beyond me? Talk of the many chances he created which the likes of Welbeck, Smalling etc missed against Swansea, or the chances fluffed by Rooney and Rvp against Sociedad or Hernandez miss against Newcastle or his pass for Mata that got us a penalty against A. Villa etc. I could go on and on.
You're right Kagawa would agree he had a poor season because he's always hard on himself and he didn't get enough gametime to showcase his talent which is equivalent to a poor season for him. However, apart from his poor display in a flat 2-man midfield against Hull and Southampton, I can't think of any poor performance in the limited games he had. Maybe you can help me out because I can't get my head around how people says he was shit when he had good performances in 6 out of the 12 games he started (the Hull and Saints game are null by the way) while the other 6 were games he was not poor nor good, considering the inconsistent way he was played. He was also our overall best player in the Ucl. I repeat everytime he played as the no 10, our attacks looked more dangerous irrespective of how poor our midfield looked in that game. For example, his debut game against Everton or the Bayern game but Rooney decided it wasn't going to be our day in both matches.
Now compared to Mata's performance in the City or Everton where he had a stinker because the midfield couldn't support him and he's not good at dropping deep to get more touches unlike Kagawa does and when he eventually got on the ball, he was dispossessed many time due to high intensity of the game. However, these are the kind of games Kagawa thrives in and takes control of the game by dropping deep which he did for the team many time against Bayern, Newcastle and Aston Villa etc. Even in the Everton game last season, he was our best player with his assured touch and composure under pressure despite playing on the wing although he wasn't productive but still better than Mata. Same thing with his City cameo when he replaced Cleverley in the 2nd half.
Talking of Mata, I can't remember any sublime pass made by him save for his backheel against Newcastle and a throughball to Van Persie in another game. The other two assists awarded to Mata were the 25 yard goal scored by Young after his short pass, similar to Welbeck's against Galaxy after a short pass by Mata. The other was another wonder goal scored by Rvp in another game. Even in the pre-season games, Kagawa had looked better and had offered more creativity than him.
Back to Januzaj, irrc he played mostly on the wing or the striker role for the youth team. And I've seen Lingard performance in the no 10 role for England u21 and Januzaj's for us to form my opinion on them. One knits the play together while the other tends to have individual highlight and when he encounters organized midfield, he gets stiffled like he did against Swansea. No one is denying his talent though.