Off course he has lost some explosiveness, athletic ability, pace but he's still explosive (far above average) and still has better then average topspeed (pace or the ability to maintain your speed was never his main strength). Vision, decisionmaking and playmaking are still at peak level ability.
But people go on and on about his motivation, his workrate. I don't believe there's much change in these things. He never had great workrate (anybody who has read books about Messi knows people have been complaining about his lack of workrate and defensive contributions since he was with Barca B and C) and his average km per game has been about the same (around 8 to 8,5 km/game) since he moved to the false 9 position in 2010. Maybe he moves less without the ball and more with it, its possible but i doubt there's much difference.
Same thing about motivation. How do you measure that? For on thing you can look at his body, since 2015 he has been thinner then he was in his early and midtwenties meaning he's following a stricter diet. Its something a lot of athletes do when they age (maybe not Suarez) to be able to maintain the ability to perform. But this shows he's certainly willing to take care of himself more to be able to perform at a top level. I think he paces himself more now, looking to exert himself when he can really help the team but to conclude he is less motivated, i disagree.
He has also become more stoic as he ages, some people can't relate to that but i see that as a plus, showing a man who is maturing.
Anyway, to me he's past his peak (which was 2010-13 and the first season under Enrique 14-15) but he's still very much into his prime (which is not the same thing as peak) and we all should be happy we can still enjoy him play for a couple more seasons and not bitch about petty things.
How do I measure motivation?
I mean, aren't those basic human psychology principles and common things in life?
If Liverpool hasn't won EPL for 30 years: they are eager to win it currently.
Imagine if they will win it in 2018/2019 season.
Do you think that their motivation to win a 2nd trophy in 2019/2020 will be 100% equally the same, as CURRENTLY after not winning it for 30 years?
I am not saying that they will walk on a pitch with zero motivation in 2020...
But their motivation will be LOWER than TODAY.
it is irrelevant whether it will drop from 100% to 90% or 80%, the point is: once when you achieve something which you have been dreaming for years, you will be mentally drained.
And you will either never reach a similar level of motivation or you will need a few years to recharge your batteries.
Haven't you heard 100s of times in sport how some team was hungrier for a success?
Or how often it is better to sell older, unmotivated players and buy, younger, hungrier ones?
Pique?
Do you think that he is as equally as motivated to win another CL like he was in 2009?
Busquets, the same?
Coaches said often after winning big trophies how they need some time off to recharge their batteries (even in the sense of motivation).
On a personal level:
I have never been to a Camp Nou match.
Do you think that it will have a stronger impact on me when I will watch the 1st match ever, or when I will watch the 8th match in my life?
Were you more emotional when Barca won the 1st CL in your life (2006 for me), or in 2011, when we have achieved it for the 3rd time?
Yes, I was happy in 2011 and in 2015, but nothing can compare to the first time when we have won it.
When you kissed a girl or had sex for the first time, were you equally as excited while waiting and anticipating for the 1st time and while waiting for the 8th time?
Messi with Argentina.
Do you think that winning a World cup today in 2018 (after waiting for it a whole life, and suffering a lot of problems, fights, pressure, emotions) would be the same for him, as winning it for the 2nd time in 4 years?
What do you think in which trophy (during matches) would he be more emotionally invested, more motivated and giving everything what he can?
The first, life-changing one, or trophies after that one?
In the first attempt it is: I would give everything to win and I will bleed on a field if needed.
4 years later, after you won the first World cup, you will have the attitude:
Ok, I will try to win it again.
If it happens=happens.
If not=we have already won it once.
In the first attempt=it is a matter of life and death, your career defining achievement.
Later it is just a bonus, to some extent.
Now, imagine winning a CL for 5 times.
Do you think a player is as equally as motivated as in 2006 or 2009?
People often reply: but they are professionals, blah blah.
Yes, but they are also humans with same brains and DNA like you and me.
When you achieve something huge for the first time, for 99% of people, it will have a bigger impact on you than achieving the same thing for the 5th time.
In that sense, I am not saying that Messi or Pique don't want to win a CL in 2019.
But in 2006, Messi was giving 120%.
In 2009 also 120%, since he was injured in semis and a final of 2006.
On the other hand, can you say that a current, old, father Messi who walks and sulks on a pitch is giving 120% in every single match?
Sorry, I can't.
I would rate it like 50-90% in majority of CL matches, compared to his younger self.
And again, that is not an attack, but a fact of life and psychology.
So:
1. every single footballer ever will lose pace after the age 28
2. every single footballer ever will lose a part of his motivation once when he achieves the biggest trophies in football
No offense, but I don't get how someone can argue simple facts of life like losing physical skills and losing motivation after winning absolutely everything in sport?