Some well-known putting gurus will preach about the importance of the putting "arc." Other renowned teachers will preach "straight back and straight through." Confused? So which is it? And what does the distinction mean?
My belief is that golf is nothing more than applied physics. If you were to design an object to swing straight back and straight through, you would insert shaft that's 90 degrees to the head. The USGA's Rules of Golf state, however, that the shaft can be no greater than 80 degrees to the ground.
Consider this: If you were going to swing straight back and through, you would straddle the intended line of play like croquet. The USGA, though, requires players to have both feet on the same side of the ball outlawing Sam Snead's croquet style putting. This creates a side-on game, like hitting a baseball, hitting a groundstroke in tennis or hitting a hockey puck. All swing in an arc. My high school physics class tells me the putter whose standard lie angle is 71 degrees is not designed to swing straight back and straight through. And in my putting research, I have found that golfers who try to swing straight back and through are manipulating the putter face closed on the back swing and open on the downswing and follow through.
Over time manipulations break down, causing the yips. If you want to really help your putting don't think about swinging the putter straight back and straight through but focus much more on your target line and the speed of the putt.