But that back 3 against a team with movement and with the pace of Mane - will not be able to push up, meaning either the midfield has to sit really deep or the team becomes disjointed badly and we will en dup under pressure and just having to punt it long and hope to a isolated Lukaku mate
a back 3 of Jagielka williams and Mori playing pushed up with the fullbacks pushed high up will be absolutely bummed as they will be forced to defend in space mate and Jagielka isn't capable of that anymore against a decent level player
Which is where the midfield comes in...
Holgate and Baines have the energy to get up and down.
If Morgan is fit and can play alongside Gana, they should be more than capable of plugging the gaps - which are likely to appear whether we play a 3 or 4 at the back pal.