How do you think they decide which bats go to which brand? Do the 'worst' performing bats go to be slazenger? Are they selected randomly? Are the more experienced makers put on to make for the 'bigger brands'?
Does Slaz have a lot of worst performing bats ? Are you stating this from personal experience ? I have a friend who uses Slaz V12 or V800 (don't remember the exact model, but it has yellow stickers) G1 willow and its extremely good - balance, pick up and ping is very good.
Its very likely that experienced bat makers are put towards making the top of line products in a brand. For example a Kookaburra Kahuna Players model bats might be made by an experienced bat-maker while the Kahuna 150/200/350 etc might be made by relatively inexperienced bat-makers. However there will be a certain level of bias towards their biggest client. If Kook brings in $100K USD of business but Spartan brings in $250k USD businesss, then its likely FCS might put their better designers on the Spartan project rather than Kook.