Disagree. I pointed out why looking at the league is the fairest way to judge the impact of Mata's absence or lack of impact. Regardless, Chelsea finished 3rd just like they did in the season before except they were title challengers were for the vast majority of the season and would have probably won if key players hadn't lost form at the end.
Also, that's a very skewed way of looking stats. You've basically taken two of Mata's most productive seasons and then compared it against the entire careers of everyone else. Doesn't really make sense. According to Chelsea forums, Mata has a total of 52 assists for them. 33 from open play, 19 from set pieces. Source -
http://forum.talkchelsea.net/topic/14112-8-oscar/page-212
Also, Total career stats
Rooney - 141 Assists from 543 games (Everton and United) - 0.26 assists/game
Ryan Giggs - 309 assists from 963 games - 0.32 assists/game
Juan Mata - 88 assists from 344 games (Valencia, Chelsea and United) - 0.25 assists/game.
That's a much fairer look at the stats. More to the point, Mata has barely looked like creating anything for us this season. For a #10 his passing is too much on the safe side for my liking and I'd like to see him force the issue a lot more.
As for Herrera, like I said I'm judging him mainly based on what I'm seeing at United and I like the look of him. He's been more productive than Mata, offers more defensively and imo brings more balance to the team. Mata's problem is mainly that he doesn't create enough. And when he's not creating he offers next to nothing. Another issue with him that moneymay touched upon is that his positioning as a #10 is too high, In the Liverpool game his average position is level with our strikers for instance.