The reason for these doubts is the line 3...dxe4 4.Nd2 Nf6 5.f3 Nd5.
Black harrasses the white bishop, white has nothing else than defending it with the queen : 6.Qe2 (diagram)
Let's look at the black replies :
a/ 6...Nxe3 7.Qxe3
...a1/ 7...c5 8.dxc5 (=)
...a2/ 7...Be7 8.fxe4 (=)
...a3/ 7...Bd6 8.fxe4 (=)
...a4/ 7...exf3 8.Ngxf3 (=)
...a5/ 7...Nc6 8.c3 (=)
...a5/ 7...Nbd7 8.fxe4 (=)
b/ 6...Nc6 7.c3
...b1/ 7...exf3 8.Ngxf3 (=+)
...b2/ 7...Qh4 8.Bf2 (=+)
c/ 6...c5 7.dxc5 Qa5 8.c3 (=+)
So it seems that black gets the better game in the majority of lines. Maybe the quiter 5.c3 is better, but that is another story.