unless you have a magical reel that pulls line from the outter portions of a reel and retrieves line from the left or right hand sideplates , line retrieves vertically through the TWS onto the spool. The picture shows the back/underside of the TWS. You aren't really able to see the grooves that well unless you break the reel completely down. I only noticed it after the reel was broke down for it's second cleaning after roughly a 1 1/2 years of use.
I own 2 Tatulas. Both have grooving in the exact same spots.