Would love to see that blog......but I think we kinda know already.
I'm not Mr Manzella, but I think we just have to accept the wrist is flat for just a moment in time, and to hold onto it is foolish (except for a few shots in golf)
The flat left wrist happens at some point during the swing, going back (not always) and coming back to the ball (almost always) when this occurs is a testament to the players skill/pivot/release/CP path and also shot selection.
One of the biggest faults in modern golf, is trying to hold onto the flat left wrist thinking it is the holy grail.
It isn't.
It's just a
WAY of hitting the golf ball. If you hold onto it/use that method you CAN hit absolutely flushed penetrating shots that will
feel compressed and amazing.
Watch out with your irons though, as the leading edge can kill ya if your lowpoint isn't amazing.
Oh, and don't try to hit the ball high enough to land on hard greens unless your have tour speed to get the ball up in the air, and even
they don't do it this way.
And also watch out for the left of the golf course too hitting down with a clubface rotating left
Oh yeah, and hitting down like that, watch out for your spin control as well
For the majority of golfer than don't want to spend 10,000 hours grooving strength to hold onto the flat left wrist and screwdriver it through the ball with PERFECT low point control then just use the line up the handle release.
Learn to release it freely, sort out your D-Plane for direction and pivot/release for speed and just go and have fun playing golf.
IT'S EASIER THIS WAY
I can also say as someone who plays with certain injuries it's a much easier way to play on the body and I'm just guessing about the instructional material, i've just held a club at chest high and swung it back to halfway and practised lining up the handle and the flick and the freedom to make a swing that is not physically gonna screw me up is very freeing.
I don't know about anyone else but I haven't got the strength or time to groove a screwdriver release or hold onto the flat left wrist through impact. If you have though, go for it if that's the way
YOU want to swing it.
There is not "RIGHT" way for everyone. Just the one for YOU