The person who says the most doesn't necessarily know the most...
Many of us rate McCarthy, many have rated Barkley very highly and are delighted he's getting his chance to shine, many have commented on Felli's limitations who had previously seen we had a beast of a player in his earlier days, many have seen tactical limitations with Moyes and many are very optimistic about Martinez and his style.
Just because some are more cautious in their comments and try not to get too carried away it doesn't mean they don't know/foresee this.