Discrepancy between game evaluation and openings

Hello,

When I was evaluating my first moves in my game 3... Bb4 was evaluated only as good. And it was not evaluated as a book move. When I rolled down openings of master games inside the evaluation that move was among the best. The pane showed only win/lose ratio, not frequency of opening moves though.

The Game Review has an opening book and if a move isn't in that opening book, it doesn't count as a book move.

My understanding is that Game Review opening book is going to be expanded. Though, just because a move is in the master database, doesn't mean it's a book move.

Thank you. And which is more accurate for first moves, fast JavaScript engine evaluation or the master database? Is 3... Bb4 weak?

The Master database doesn't have any evaluations. It just shows what positions have been reached in the past.

It should also he noted, the game Explorer shows games with positions that have all the pieces on the same squares the given move is just games with those pieces in those new positions and not alwayss the actual moves.