[Daryl]

Some say that vertical swing planes give higher rate of closure of the face in the impact zone (I haven't been able to make my mind on this statement) so maybe the "release low and left" is an anti-hook feature ?

It's true. The more Vertical the Plane, the faster the closing ratio. But that's easily evident if comparing a nine iron to a driver. It's also important, to understand, when playing the ball aft a few inches that the plane must steepen to accommodate the Angle of Approach.

I don't think Tigers Plane Angle is the problem. But then, I don't think that Plane Angle is hardly ever the problem.