It's because of the system that Koeman is employing 4 -3 -3 (the front three looks to be Striker, Right Wing, Left Wing), we are pretty good with Tadic on either the right or left (more lethal on the right at the moment because his link up play with Clyne is excellent). Jay Rod is currently out injured, so we don't really have a natural extra winger on Premier League quality (yes Isgrove is out injured, and seemed to be in Koeman's plays)
Shane Long at the moment seems to be a make-shift winger, but isn't playing too wide because he's usually more central (or has been instructed to play more central).
Therefore we are linked with Townsend (RW), Mane (LW), Redmond (RW), Kacaniklic (LW).