Wes shot 41% from 3 last season (for the Blazers). Memo shot .313.
The Memo extension was stupid. The Jazz had just been knocked out in the first round of the playoffs, everyone was sick of Boozer (and seemingly he was gone in another year), and it should have been obvious to the FO that the Jazz weren't going to be title contenders any time soon. There was nothing to gain in locking Memo up early, and the Jazz ended up losing their best wing player with the extension.
And their best wing player since Hornacek. Who happened to also be on of their youngest players as well (which even if Deron was still traded, Matthews is a piece you keep and can build with)...