Witsel is not a rubbish player and he does bring certain things, but at our level we need more. Like I said before he is a 6/10 player, but we need more than that. As for defensively, he is clearly not great. He is OK, because he lacks speed and mobility. He is no where near Kante, Fernandinho, Fabinho, Casmeiro etc, because he lacks speed and lacks mobility. Delaney is the best midfielder we have defensively. If Witself had Delaney's level of defensive cover, then actually I think his on the ball skills would be acceptable, but he does not. I agree there are times when his slowing the game down is our benefit, but teams have worked him out and it's not just elite games, it's the likes of Augsburg, who stop him. Here are clips of Busquets. In my opinion, we need a 6 like him. Here is Busquets VS Madrid to get my point across. Now Busquets was the best in the world, so I am not asking for Witsel to be at his level. This is just one game and I can't easily show Busquet's movement. However, for that video against Madrid, forget his nimble feet in avoiding the press. Just look at how quickly he makes passes. He virtually never takes more than 3 touches of the ball and quickly passes into the attacking players.
I remember seeing Barça play a summer friendly against Chivas at Candlestick Park (a decrepit, terrible baseball/NFL stadium which has since been torn down) in San Francisco a decade ago. Obviously I was excited to see Messi, Xavi, and Iniesta, and had no idea who Busquets was as he was only 21 or so. Even though I didn't really know what I was watching, I came away thinking "geez, that Busquets guy seems to know what he is doing." Good times. I watched the Köln match again and it didn't look that bad in terms of individual performances. The story was more that Beierlorzer came out with a simple and effective tactic to clog up Dortmund's central buildup and force the ball wide to the fullbacks. I'm not even sure it would have been better with Dahoud or Brandt in place of one of the double pivots, as their ball progression might have been offset by increased mistakes leading to Köln counters. If Favre wants to continue playing 4-2-3-1 he might need to play a different fullback pairing rather than the old-school vertical style of Schulz and Piszczek. Especially since there is no target man up front to serve as an escape hatch.
Maybe you are right on the Koln match, I have only watched it once. However, your last point is the key one. We cannot hit it long to any of our attacking players. We have no target man, but even if we had a Bale or at a much lower level a Mikel Antonio, we could hit it long to them on the diagonal. This is why we have to go the Barca/City route and be excellent in the build up from every player, with excellent technique. I think in the future Schulz and Brandt will compliment each other well. Brandt will drop deed and come inside, helping with the build up, whilst Schulz will exploit the space left out wide. Hakimi or Morey, are both good in possession and might have to start. Thorgan is injured for a few weeks with a rib injury, so Brandt looks set to start on the left.
The target man approach does not work anymore. Even if you have an Icardi or Lewandowski. Nowadays defensive systems are way more than 2 CBs being helped out. Even before the ball is allowed to be sprayed forward you have a tactical setup to prevent that. Against weaker opposition it works but not against tough ones. This explains why Lewandowski is known as a big game flop. He has a very high level but it cannot be raised against the best in crucial matches. In the last couple of years, BVB has chained him up when they beat Bayern but the ones they lost usually in the Rückrunde, they let Lewandowski go free because they simply did not show up defensively. We saw it twice under TT and again under LF. The less about the Peters the better. They had no clue what they were doing.
The target man works, depending on the target man, the players around him and the defense he is up against. If Drogba was about then the target man would work. France just won the world cup with an average target man, and Chelsea won the Europa League with the same average target man: Giroud. Lewandowski is a complete striker and excellent at many aspects of the game. In recent years he has missed key chances in the big games, noting to do with his overall game. He just has not been clinical and for me Lewandowski was never eve as clinica as say Auba, but had a lot more to his game. Anyway Witsel is injured for a couple of weeks, I am praying Favre goes for the Weigl and Dahoud. I really don't want Delaney to start, because this will make things worse, but I bet Favre goes for Delaney.
For every example of a successful target man, there are 5 who are flops. Benzema stopped playing as a target man and helped Madrid win those CLs. Napoli plays a fluid front 3. Juventus played last season with Ronaldo and Mandzukic in a fluid attacking formation. Liverpool, Ajax, RBL, Atletico, Barca and City are all example of teams without a clear target man. Edinson Cavani has probably played as a target man for 2 seasons and he has been playing at PSG for 6 years.
This is more to do with the lack of good target men about. A good manager makes the best with the players you have. We are not playing Alcacer, because we prefer his game to Lewandowki, we just dont have a Lewandowski.