Well, you don't have to narrow it to death specifically. Search through the annals of fan and professional criticism and you'll find many complaints about Trek captains being mishandled at various times. There are plenty of people out there who think Kirk was mishandled in TMP or much of the third season of TOS, or that Picard was mishandled in NEM or in the novel Ship of the Line
. I think Kirk was mishandled in TUC. Many think Archer was mishandled in season 3. Many think Sisko was mishandled in Rough Beasts of Empire
, though others have reconsidered upon reading the subsequent duology.
So to claim that Janeway is the only captain who ever got handled badly, and that it must therefore be because she's a woman, is simply untrue. Don't get me wrong, there's plenty of sexism in the world that legitimately needs to be acknowledged and fought (as a certain not-so-honorable Mr. Akin of Missouri has so vividly demonstrated in recent days), but that's exactly why there's no sense inventing imaginary charges of sexism and wasting energy on the wrong battles. Male Trek captains have not been immune from mishandling either.