I absolutely agree that Lucas is the better player at the moment, and that overall he's a much better player than he's given credit for still by many United fans, but the crux of the matter is that Lucas reaching this level is a big success while if Anderson was at that level I think we'd still be expecting much more, and that's because Anderson's shown a level of quality in spurts that Lucas hasn't and (IMO) likely never will. He's potentially in a different class altogether. He's got the ability to dominate the midfield area, to be our midfield general, and he's absolutely got the on-pitch personality/attitude to become that player - he wants to influence the play. Lucas isn't that player, he's a 'water-carrier'. That's not to downplay his contribution, it's still an important role to play and one that demands a great level of discipline and intelligence and he's well on his way to establishing himself as an important player for club and country, but I still have every belief in Anderson that he can be the key midfielder in the team, the one midfielder that's constantly influencing the play and driving the team forward.
That said there's absolutely no denying Anderson hasn't progressed as we'd have liked or expected, whether that's primarily because of attitude, fitness or tactical problems is up for debate but it isn't because of a lack of quality. If he regularly picks up medium-long term injuries then yeah, he'll probably not develop into the player he can be. Or his attitude/tactical problems could lead to him just simply not making it with either a club as big as us or just our particular club. There's nothing unreasonable about having doubts about whether this may happen...but I just don't understand why opposition fans can't see his quality bubbling underneath, which is quite clear from the 'has done very little of note' and the 'talent yet to be seen outside Manchester' comments.
As for his slow development, what some even call a regression, I think there's some similarities to Rooney's development in recent years. He was seen as a 'better player' because he played with freedom, raw quality and he played on instinct, and when he was given a more structured, disciplined role many felt that he had stagnated, that he'd lost that creative spark that made him so brilliant and even went as far to say that 'we'd ruined him'. But his creative spark was there for all to see last season, that ability to dominate the play creatively was still there and it was all part of a long-term development plan to make him a more rounded player. It's obviously not an easy or quick transition.
I think we'll see the same with Anderson, once he gets the basics sorted in terms of midfield play he'll show his natural ability to be a creative force and a dominant player. I do think he's not given enough credit for improving some of his passing, positional and defensive game. In his first season he showed an eye for a difficult pass but he gave it away often and carelessly, and was closer to Giggs than any other player in terms of pass completion rate iirc. Now he has a very respectable rate of 83%, only one less than Fletcher for example. Added to that I don't know if it's just me but I think there's been real progression in his long passing game.
) there's every chance this will be his proper breakthrough season (with his best years still ahead of him)