Flex vs no Pulling Lineman

[Big_Coconut]

Ive been studying a lot of flex defenses lately im really intrigued by the concept and plan to add it to the Dc 4-3.  My question is, the flex was made for offenses that pull often would that mean that running the flex vs a Power I team that doesn't pull would be a huge mistake?  If you only flex one side of the line which side should be flexed, strong/weak?

[BillMountjoy]

Ive been studying a lot of flex defenses lately im really intrigued by the concept and plan to add it to the Dc 4-3.  My question is, the flex was made for offenses that pull often would that mean that running the flex vs a Power I team that doesn't pull would be a huge mistake?  If you only flex one side of the line which side should be flexed, strong/weak?

SEE ATTACHMENT: