Although I rated Doherty highly when he was at Wolves, there's no argument that he was hugely disappointing for the better part of two seasons when he first joined Spurs. Turning point seemed to be when Kulu joined us, that provided him with support down the right flank and enabled him pretty much for the first time to play his natural game for us. Beware of Aston Villa full backs anxious to please their manager by any means fair or foul, and hopefully he can return fully fit next season. We need him to, Royal at best is only a replacement option when needs must, and even if we sign him I'm not sure that Spence would be a better option then Doherty at this stage.
For me Doherty isn't an orthodox wingback because he doesn't think in straight lines. He doesn't hug the touchline and doesn't just want to overlap. He can make a run from the right back area to the penalty spot and nobody is expecting that. Just don't expect him to be a marathon runner or a sprinter. He has the football brain and technique though.