I have no idea if MPTCP on its own is supported by the F5 (no hits in devcentral nor the supportpages) but if you have a MPTCP device in front of it then the flows are just regular TCP-sessions.
However reading a description of MPTCP:
"
MultiPath TCP (MPTCP) is an effort towards enabling the simultaneous use of several IP-addresses/interfaces by a modification of TCP that presents a regular TCP interface to applications, while in fact spreading data across several subflows. Benefits of this include better resource utilization, better throughput and smoother reaction to failures.
"
it sounds somwhat like regular setup of F5.
When you setup a VSERVER in F5 this VSERVER will DNAT the traffic towards a pool of members. The loadbalancing algorithm can be for example roundrobin.
If you do this for a pool of webservers you can spread the load while each flow will go to a dedicated server. For example if a client requests 9 pictures and you have 3 members in your pool (and use roundrobin as algo) - the result will be that server1 gets request 1,4,7, server2 gets request 2,5,8 and server3 gets request 3,6,9.