The thing I noticed and certainly it has improved my game tenfold, is every once in a while you need to let go of the RT/R2 trigger ! Although pace is extremely handy the only real positions I see pace as a need is your front men if you like playing lots of long through balls and maybe your CB's to defend against lots of long through balls. I use IF Godin who has 67 pace and he is god like ! doesn’t let a thing through, I’ve also had very good experience with Hummels too who again is “slow”.
I use Alonso (55 pace) - Xavi (60 something) - Khedira (59) the pace numbers are off the top of my head so not sure if they are 100% correct. But you know what them 3 have prob been the best midfield I have ever used. Sure they are slow and are not going to out run anyone. But all 3 can pass like a freaking beast Alonso and Khedira can hold the ball like no tomorrow, Xavi is a bit more nimble and will get shoved off but his passing ability exceeds anyone I have ever used in this game.
I’ve tried 41212 a few times and I personally just cannot play well with two ST’s. For me I find that one just gets in the way of the other and causes more problems that solves. I play 433(3) the one with two CDMs, some might look at it as being too defensive (especially with Alonso and Khedira both being M/H) but I have no problems creating chances.
I try being tactical with my play. I have two maing styles depending on how my opponent plays with my current BBVA team. If he is hyper aggressive lots of pressure then I simply counter attack my midfield will punish him because of that high passing asset and my front men being zippy buggers. I don’t need or expect Alonso to get the ball then sprint all the way up the field to shoot on a counter it simply will not work, so I will pass it through to Messi, Griezmann or Di Maria they can do the running and/or crack in a scorching goal

Alonso can’t. If my opponent is playing at a slower pace or just trying to cross spam, I will play slightly more possession based and will most likely hold it in midfield more often. This is to wait for my chances and my CDM’s can hold the ball well so why rush, he will eventually make a mistake pull a CB out too far or whatever and which point I will take full advantage of that. I also find it tends to annoy cross spammers if you hold the ball in the middle of the park

Obviously I might chop and change formation mid game if it’s simply not working, so I might change to false 9 bringing Messi to CF and most likely sub Neymar on for Grezmann. That said I have also changed to a 4231(2) the one with LM/RM brought my wingers back subbed Xavi off for Iniesta as I think he is better at a CAM role. My reasoning was my wingers were simply being abused that far up and was not getting a look in bringing them back a bit in that one game worked because all of a sudden what was working for my opponent was no longer working my positioning was different which threw him off and ended giving me more space and an eventual win.
You need to be more flexible with you play, a one rule fits all will not work. Sure you can play the OP over the top ball over and over again and to some degree it will work, but you will eventually come up against someone who knows how to defend well against that and will rip you apart if you have no other tactic.
Ps I also have no idea why I have written this massive post because it most likely won’t be read.
TLDR: Stop chopping and changing learn how to play various styles and formations. Just because you pick 41212 as you “main formation” does not mean you need to play an entire game in 41212.