I would recommend a light sanding for two main reasons,
- To get a smooth surface so that the new scuff sheet sticks to the most amount of surface area, as there could be some rough parts that have lifted with the removal of the old scuff sheet.
- To give the bat a new surface, as there could be dead wood depending on how old the bat is - this will prolong the life of the bat.
I would get some fine/extra fine sand paper, something like 300+ will do a decent enough job for you as you're putting a scuff sheet on it. I would also recommend lightly sanding across the grain to stop any possible splits lifting.