I think we've more goal threats in our team and if they don't sign anyone and have an over reliance on Rooney it'll cost them dearly.
Benteke - (1 in 2 striker) 15-20 goals
Sturridge - (2 in 3 striker but injury prone) 15 goals
Firmino - 10 goals
Coutinho - 10 goals
Henderson 5-10
Milner - 5-10
Lallana 5-10
Ibe, Markovic, Origi and Ings 5-10
Above are players more than capable of scoring the 70+ goals needed for top 4.
Rooney - 15-20
Depay - 10
Mata - 10
Herrera - 5-10
Feilani 5 goals
Schweinsteiger and Schneidelin - 5 goals (neither known goalscorers)
Have Young, Wilson, Valencia add a few more, probably but nothing major. I think Hernnadez is on a massive downward slide and if not moved on will struggle to make an impact 5 at best.
Of course they are in the market for another attacker so it could all change but so far they've lost the goals of DI Maria, RVP and are unlikely to play one of their main sources of goals last season Feilani. Maybe even Herrara also.
In contrast we've add Benteke and Firmino as well as a fit again (hopefully Sturridge). I think as things stand were in a better position to finish 4th. Pedro would be a big addition if true though.