Stability is Jorge's problem not so much Rossi's.
Corner entry and turnability goes together with braking and acceleration/controlability on the gas, i.e. chassis geometry and weight distribution, the opposite is true for corner speed and stability, as the M1 chassis was optimised from 2011.
With a shorter wheel base and less weight on the rear, you have better charactersitics on the brakes (weight transfer, front tyre heat build up and grip, 2013 issues all season) as is the 2014 M1 but a less stable bike, as a matter of fact you can watch this motogp video and notice @ 0:00:36 how Lorenzo M1 moves on the brakes and his reaction back in the stands. www.motogp.com/en/videos/latest+videos#2014+Qatar+Rewind
Rossi is not so much concerned about bike movements, he used to steer the rear on the brake at corner entry and rides a lot more on the front (500, RCs, M1s) as well as sliding them on the gas, more on the Hondas than the Yamahas but still he was back-wheel steering all his bikes after the 250cc.
This year, the M1 chassis have changed (repositioning of the engine in the frame, wheel base, flexibility etc):
Corner entry, braking (front end grip due to lack of heat build up), turnability on the brake(s), control on the gas were issues with the 2011/13 chassis and last year the M1 was loosing a lot to the RC in those areas.
I apreciate we can have such exchanges without flaming, cheers.
Oh, i forgot, Zeelenberg is Lorenzo manager, he has ZERO experience of powerful bikes and was a mid-grid 250 cc rider, this explains a lot.