The days of 'getting the ball' being the sole determinant of an acceptable tackle are long gone and have been for years. The referee will clearly have deemed Bannan to have endangered an opponent which is fair considering his studs were up went straight into Winks's leg. Whether or not you agree with the way the rules are set out, when properly applied in this context that has to be a second yellow.
And ultimately, that is a crazy tackle to go for while on a yellow and I'm sure in retrospect Bannan would agree - however contentious the first yellow may have been.