I was just browsing through our pre-season games and looking at when we had all five of them available. We never had all five of them on the pitch together. It's a very, very small sample of games of course (3 or 4, which include the Bayern and Atletico game).
The closest we came to fielding all five was against Bayern, where we set up differently compared to our usual starting formation. Lallana was on the bench for that one and later came on for Mane. I actually doubt that we'll see the five of them together in a starting line-up
very often. Only in games at home against teams like Huddersfield who have no intention whatsoever of attacking, then we'll likely need them all to unlock the defences. I can't see him do it away from home for example, where we've been pretty poor defensively.
Against the bigger / better teams, in high tempo games where we need our pressing, this is our strongest starting eleven for me:
Firmino, Salah, Mane and Henderson are nailed on starters for Klopp I think (for me too). That leaves the #8 spots for Wijnaldum, Lallana and Coutinho. The midfield trio of Wijnaldum - Henderson - Lallana bossed (big) teams on a regular basis last season. That's a very balanced team, all three of them can cover large distances during a game, they press well, they're good both defensively and offensively. Coutinho, in my opinion, isn't suited to that midfield #8 role (in our 4-3-3) in a high tempo game where our pressing in midfield is vital. He's the best out of the three offensively, but he offers little defensively in comparison to the other two, something we need from our #8's in our usual 4-3-3. A midfield of Coutinho - Henderson - Lallana just doesn't look very balanced to me.
There were a couple of times towards the end of last season when coutinho was pushed into the middle (which is his best position in my opinion). I thought coutinho would play in the 10 role and lallana in the 8 but klopp had it the other way round and he was right to do so.
I can't see both Lallana and Coutinho in our line-up without Mane, Salah or Firmino missing out. When we played Coutinho in a more central role (indeed Coutinho wide in the diamond and Lallana as #10 as you say), we always had both Wijnaldum and Can in the line-up too to make up for his lack of defensive qualities. So if we have both Henderson and Wijnaldum (who have always been starters when fit, Can always missed out then) on the pitch, who is our 3rd midfielder, or when playing a diamond, which of the wide players misses out?
Then we're not even talking about Chamberlain who seems to be adapting reasonably well. Klopp will have some right headaches after the international break. Don't think we've ever had so many quality options in the front 4 / 5 to choose from! All of them are able to play in different formations too, so it's likely that we'll see quite a few different set-ups I think.
It's like the whole Wijnaldum thing; he does so much of the dirty work that Lucas used to do, but he does it further up the pitch.
People just don't see it.
I honestly don't get it when I see someone writing / questioning what it is exactly that Wijnaldum offers or what he does on the pitch. Other than injuries / the very odd game of rest, he has started almost every single game under Klopp. It's funny how everyone watches games differently and come out with completely different conclusions after watching the same game.
I for example thought Wijnaldum had a great game against West-Ham. That of course disappears into nothing when you see Salah's / Mane's performances and their assists / goals.