Midhaul
The 'Bus they are leasing is an A330-343. Trent engines and not the very latest bells and whistles HGW version.
That makes it the ideal plane for Canaries midhaul sectors or packed to the rafters with Alicante and Palma passengers. I'd expect it might see plenty of Dalaman and Paphos too. That A333 variant might not be ideal for flying over the pond but as for the LS and Holidays core routes it would fit quite nicely. High capacity, medium range.
LS also has to integrate BLK's flying into the MAN operation for next summer's forward bookings and hopefully it'll swell those ALC and other routes for them. Having a people mover on the strength is a no-brainer and the A330-343 fits the bill nicely.