I haven't read through every comment as no time (as at work

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I don't know why JB thinks the Macca lacked outright pace - yeah, in terms of an outright pace advantage like he enjoyed in the Brawn, he is right - but that was a freaky one off based on rule advantage , as was the Red Bull outright pace the following year.
I think the Macca was very close on pace to the Red Bulls in quali trim, and for a good portion of the season, was probably faster (or at least equal) in race trim. I recall a few races when they just didn't get on top of the circuit/conditions - but overall the Macca pace was very good.
My feeling is that JB simply doesn't like change - and perhaps takes too long to adjust. So a changing car, tyres, and regs will have upset him. Add to that new tracks and any tracks without a smooth 'style' track and smooth handling, he just doesn't seem to be able to cope as well as others (IMHO). Brazil was a good example, JB was as smooth as silk in that car and on that track in those conditions - and as has been said many times, when it (car, tyres, track, weather, etc) is absolutely spot on - he looks really really fast (and almost effortless!).
For my money, JB is more like an artist, or musician - when the 'vibe' is flowing he is relentless, perfect even, but when it's not he is 'just another driver' - and that is definately not meant to disrespect him! In a way, I think Vettel is the same (but since he generally has had the fastest car, it's hard to demonstrate) - but sometimes he just seems so calm and serene in the car - usually out front - and just munching into the miles on the track in a smooth and effortless way.
By direct contrast, we rarely see LH or FA driving like that (unless with a significant performance or race time advantage, so that they are 'cruising') - they nearly always seem to be 'pushing' the car to its limits, sliding, making little mistakes, etc, etc. That is certainly the impression I have got from recent seasons anyway, but I accept that of late LH has 'toned down' a bit. I don't know if this is their racing/driving 'aggression' or driving 'style' but the difference is noticeable between the top drivers.
Returning to the 'lack of pace' comment - I simply think JB hasn't always been able to be 'smooth' in the MP4-27 and that has perhaps affected his 'appreciation' or 'belief' of the actual cars pace - if that makes sense. I recall a couple of occasions where he said he couldn't see where LH had got the pace from (or am I just remembering wrong?)