Everyone has a video that can prove something.
However, I think it's fair to assume Bertans is not going to be a plus defender. That's a given. But we know that about several Mavs players. We knew it about Seth Curry and we know it about Tim Hardaway. We know it about Powell. We even know it about Brunson. Josh Richardson couldn't remain in the lineup even though he was considered at the time to be a plus defender. If J Green could hit outside shots with NBA regularity, he might be in the Mavs starting lineup. If you can't his shots, you can't have a lot of minutes.
Bertans will be a net positive in some games, but I don't expect his minutes to increase substantially until we know his shot fall at a good percentage.
However, I think it's fair to assume Bertans is not going to be a plus defender. That's a given. But we know that about several Mavs players. We knew it about Seth Curry and we know it about Tim Hardaway. We know it about Powell. We even know it about Brunson. Josh Richardson couldn't remain in the lineup even though he was considered at the time to be a plus defender. If J Green could hit outside shots with NBA regularity, he might be in the Mavs starting lineup. If you can't his shots, you can't have a lot of minutes.
Bertans will be a net positive in some games, but I don't expect his minutes to increase substantially until we know his shot fall at a good percentage.