In another thread I created regarding a query about the name of the 7...Nbd7 variation of the QGD, I mentioned in passing the line in the title of this thread, I'm interested to discuss this in more depth with any others that are knowledgeable of this line, or are interested in looking into it.
I like this following set-up used by Grachev and Zvjaginsev in particular but game I used below was from Jianu-Marin, 2014: 4...Nbd7 5.Bf4 dxc4 6.e3 Nb6 7.Bxc4 Nxc4 8.Qa4+ c6 9.Qxc4 Nd5 now there are several options but will just show most testing: 10.Bg3 Qb6 11.Qe2 Bb4 12.0-0 Nxc3 13.bxc3 Bxc3 14.Rab1 Qd8= there is a game that reached this position Jianu-Marin 2014 that ended in a Black win.
The alternatives on move 10 for White seem to be 10.Rc1, 10.0-0 and 10.Be5, all of which lead to nothing as well as far as I can tell. If anyone knows a path to +/= for White in this line I would be interested to see it. If not, this could force White players into abandoning 5.Bf4 from the 4...Nbd7 move-order and going back to 5.Bg5 which is more interesting to play imo.
Further to the above I also think the following line is worth considering as an alternative to 5...dxc4, instead play 5...c6 and we have the 5.Bg5 Semi-Slav position except the bishop is on f4 instead of g5 for White, and Black has the added move Nbd7. I'm not sure if this favours either side but I think this is an interesting line for further research as both Kramnik and Carlsen tried it out once each, both were blitz games played in 2014. Carlsen drew his against Grischuk in WCh blitz in Dubai, 2014. Kramnik lost against Aronian in Norway Blitz, 2014. I prefer the way Carlsen handled the position, although I prefer a different continuation to what Carlsen played in his game. I have included very brief analysis of 5...dxc4 and 5...c6 in pgn games below:
I would be interested to see if anyone can come up with a path to +/= for White somewhere after 5.Bf4. If not, hopefully we may see a return to 5.Bg5 in the future. I would rather play either of the two aforementioned lines as Black, than memorise the theory needed to play 4...Be7 5.Bf4. I also think both lines pass the "Carlsen test", by this I mean: I don't think Carlsen would accept a draw in either of these lines for Black.