I'd LOVE to answer. Because illegal moves...well, that problem has not been an issue at all for years with Chess engines, and I don't believe chess.com wrote one of their own. Plenty of good ones to use.
My only problem is, you're showing an off game position (maybe you reached it in analysis and mistakenly shown it to be the main line? or switched lines?
Here's my issue:
Here's a link to the game:
http://www.chess.com/livechess/game.html?id=22686860
Obviously same game. Too close a position to the one you put:) But the position you placed in the diagram never happened in the game.
For one thing, in the game, by the time black's queen played itself to g5, the f and g pawns were already off the board. So you're just showing a position that never occured.
More to the point, the position you show in the first diagram, not only never happened in the game, but COULD have happened, had he played 37...Qg5 instead of 37...gxf3, which he did in the game, which should have given white a clear win (with the simple 39.Bxc5 with a won position, instead of 39.Qxf3? which reaches a lost position).
37...Qg5 is the move that, HAD it been played, would have kept the game going and would have reached the position you gave in your diagram.
So it stands to reason that you would get a line showing how your opponent could have done better (to show your mistake).
But there's obviously something strange going on with position synching... Some analysis seems to talk about different positions than the ones you think, so , if you don't mind, I'd love to see the full computer analysis you were given to the game, not just this line you put, ok? otherwise...with a position not of the game, perhaps the analysis was of another subline. If I could take a look at it, I may get a better idea and be able to help.
I havent checked to see if this is already an ongoing topic of discussion, but I have a small bone to pick with chess.com, and I was curious to know if others out there have had similar experiences. As part of being a diamond level member I get access to supposedly "higher" rated analysis of 2500 level strength. Whenever I lose a game in live chess I usually submit the game for computer analysis so that I can see where I went wrong, and what I could have done differently. There have been several instances lately, where the computer shows either one of my moves to be dubious or outright blunders, and provides a better line to show me the error of my ways. However, when I go through the computer provided line it looks to be completely losing. When it first occured I said to myself " no I must be missing something" there is no way a computer of 2500 level strength would miss such a basic winning line. This has happened a few times, and today was the final straw, that led me to post this article.
I lost a game earlier today, and submitted it to chess.com for computer analysis. Upon return of the analysis I begin to go through it, and as usual the computer pointed out several errors that I made during the course of the game. However, in one particular line it told me to move my pawn from f3 to f2. Now I was white in this game, so I'm hoping all of you chess geniuses out there will understand the inherent problem with this suggested move. If you cant quite get it let me spell it out for you...PAWNS CANT MOVE BACKWARDS. As you can imagine I was completely dismayed by this line provided. It has made me doubt the validity of the computer analysis altogether. As I stated previously this isnt the first time this has happened...this just happens to be one of the most blatant errors I have ever seen from the chess.com computer.
So my question to all of you is have you received flawed analysis from the chess.com computer? And for the people who run the site, are you aware of this issue? Is anything being done to remedy it? I will post a few of my games, that I have submitted for analysis, in which the lines provided (which the computer claims give me an edge) are completely losing or at the very least inaccurate. If someone can see a way that I can hold the position, or validate that the computer is in fact correct, please feel free to call me a fool and illustrate the winning continuation!! Below you can find the position in which the computer recommends the best continuation for white is to move his pawn from f3 to f2. Ill copy and paste the full recommended line next to the diagram.
38. f3f2 Rxf2 39. Rxf2 exf2+ 40. Qxf2 Qc1+ 41. Be1 Re8 42. Kf1 Re3 43. Rxe3 dxe3 )
Here is another game of mine that I had analyzed in which the computer claims I have a slight advantage, and then the line it provides shows me mating my opponent. Its clearly not forced mate, and there are a lot better continuations for black. I just cant believe after I read the analysis that the computer shows me mating, and then claims "white has a slight advantage". If checkmate is only a slight advantage then I would like a slight advantage more often!!
Now in the game my opponent played ...Qg4, and the computer claims this move is a blunder (which it is because now after Kh1 the bishop is trapped). Here is the line the computer provides in lieu of what was played: 18... Qg6 19. c4 Rad8 20. Rd2 Bc8 21. Rc1 Bg4 22. Rcc2 Bf5 23. Rc3 dxc4 24. Qxd8 Rxd8 25. Rxd8#; and after Rxd8# the computer says that white has a slight advantage.
There are several other games that I could post, but I think by now anyone reading this gets the point im trying to make. Really the purpose of this article is not to bash on chess.com, but to provide constructive feedback so that we can continually improve the site, in order to help all of us improve on our chess playing abilities. I really enjoy the convenience of clicking on "computer analysis" after I finish my game, and getting some feedback on where I went wrong, but if the analysis is flawed its really hurting my play rather then helping it.