But the manager concedes that, for all Everton's shrewd business, it may only allow them to stand still, at least in terms of league position.
Koeman said: "We know it is a tough start but it is all about, in 38 games, getting the points".
"We can improve and spend money but everyone can improve and is spending money".
McCarthy, who has been linked with a move away from Everton, sat out the final pre-season friendly against Sevilla on Sunday with Koeman insisting the former Wigan player wasn't fit. "If all the big ones are really strong and doing what they need, it is very hard". "If you look at my team this weekend, and the bench, you can not compare it to the big six".
If they can get Sigurdsson then they will be a certainty for seventh.
Koeman clearly no longer considers returning star Wayne Rooney as an out and out striker and, rather, the Dutchman is looking for a collective effort to replace Lukaku's prodigious output.
Koeman said: "To replace Lukaku is really hard".More news: Spurs beat ten-man Newcastle 2-0
More news: Trudeau confirms release of ailing Canadian pastor imprisoned in North Korea
More news: Depression Symptoms: Instagram Algorithm Could Detect Disorder Better Than Your Doctor
"I don't say impossible, but 25 goals is a lot and we have to find other ways and productivity from other players and we like to bring in other players in".
"We have the experience of what we need to pay for players who came here and had one year of contract".
"We have brought some players in like Klaassen and Sandro Ramirez and we would like to bring some more in".
Stoke could complete the signing of Bruno Martins Indi before the game but it will not be done in time for him to feature.
"It's not an easy fixture under any circumstances".
"It's one that's frustrated a lot of people, not least myself, but now it's likely to get done unless there's any last-minute hitches, but we don't anticipate any".
"We have to concentrate on what we do and hope they get a little bit enveloped by all the stuff that's happening on the periphery".