"A better move" recommended by chess.com but almost never played? I played a game starting with


d4 d5 2. c4 dxc4 3. Nc3 a6 4. a4 Nc6 5. Nf3


Black's next move is 5... Bg4 and it was considered by chess.com as


  Inaccuracy (-0.28) A better move was 5... e5 (5... e5 6. d5 a5 7. e4
  f6 8. e2 b4 9. g5 O-O 10. O-O)




But according to 365chess.com, the move 5... e5 is seldom played while 5... Bg4 is more popular with a high winning percentage for black. Why does chess.com consider 5... Bg4 as an inaccuracy?
Chess.com listed this as an inaccuracy because the engine is running at a limited depth, only looking at each move for a few seconds. 

When I put the position after 5...Bg4 into Stockfish, it gave an evaluation of +0.12 at 16 ply. But at 18 ply, the evaluation dropped to -0.38. Most likely if you had run the analysis at "maximum" (which I realize is locked for non-premium members) the engine would have analyzed enough to know that 5...Bg4 was not an inaccuracy.