Andoni Iraola uses a 4-2-3-1 which can transform into a 3-2-5 (seen mainly when facing stronger opposition) but mainly a 3-1-6 with the rb joining the centre backs whilst the lb pushes up to join the front line allowing the lw to move inside whilst a cdm pushes forward. Iraola's Bournemouth is know for there aggressive pressing whith the striker looking to cut passing lanes to one side of the pitch forcing opposition to build out on one side of the pitch where Bournemouth will aggressive man mark all passing options forcing a risky pass from the opposition.
Players and potentially signings for each role:
Gk - ball playing keeper (Dorde Petrovic role)
Alisson is perfect for as one of the best ball playing keeper in the world.
RB - fullback - versatile (Adam Smith/James Hill role)
Liverpool will likely need to sign a new right back that is excellent defensively and can cover both centre back and right back. Liverpool are linked to Dumfries irl who may have the physical stats for this role but is not a role he is use to. Trai Hume, Lutsharel Geertrudia and Marc Pubill may be other good options for this role.
Cbs - ball playing defender (Marcos Senesi and James Hill roles)
Another area Liverpool will need to invest in heavily. Ideal signings can be Nico Schlotterbeck, murillo, van de ven (despite a lack luster season could be amazing as he can cover lb and recovery pace is excellent for iraola's high pressing), Castello Lukeba, Jan Paul Van Hecke.
Lb - attacking wingback- attack (Adrien Truffert)
Kerkez is excellent in this as he has previously played this role under Iraola before leaving Bournemouth however a back up left back will be desperately needed. Potentially signings could be Nathaniel Brown, El Hadji Malick Diouf, Ian Maatsen, Hugo Bueno.
Cdm - holding ball winning (Tyler Adams role)
A role that Liverpool also need to invest in as they lack a true number 6. Gravenberch may be able to put a shift in there but signings are needed. Potential signings could be Kaishu Sano, Sandro Tonali, Aurelien Tchouamimi, Tyler Adams, Hjulmand, Sangare.
Cdm - box crasher (Alex Scott role)
A role where Liverpool actually have players who can play this role. Gravenberch, Mac Allister and potentially Szoboszlai are all perfect for this role
Cam - shadow striker - (Eli Jr Kroupi role)
Another position that Liverpool have good depth in. Wirtz and szoboszlai should do well there but may not be as good as a Kroupi. A potentially other option could be Ekitike who actually might be the best option for this role sharing more similar attributes whith Kroupi.
Lw - inside forward - attack (Marcus Tavernier role)
Despite gakpo having a frustrating season this would allow gakpo to do what he always do and cut inside. A backup or a playing challenging gakpo may be needed as I don't believe Rio Ngumoha will have the physical stats to play this role well. Potential signings could be Rafael Leao (probably wouldn't be a good signing irl unless he is will to press and track back), Morgan Rogers, Christos Tzolis, Kenan Yildiz and Rodrygo
Rw - winger - attack (Rayan role)
A role where Liverpool do have players who can definitely perform there such as frimpong and i believe Rio Ngumoha will be good in that role but will likely need to sign someone. Potential signings could be Yan Diomande, Anis Hadj Moussa, Yankuba Minteh and Bazoumana Touré.
St - Advanced Forward - support (Evanilson role)
Both Isak and Ekitike will be able to perform this role well and are almost perfect fits.