The problem is that what we've seen of Jadeja in international cricket is not the best that he can be.I like you Z, and I generally agree with your opinions, but with due respect, Ravindra Jadeja is ████. If he's our best all-rounder, then we should accept the fact that we don't have an international class allrounder and pick the extra batsman. As far as WC is concerned, we can get away with Raina/Yuvraj/Sehwag delivering 10 overs of part-time spin in subcontinental tracks.
He's shown in Ranji cricket, his first season of IPL, and his early days in the ODI side that his bowling is actually very good. He's good quite good control and can vary his flight and pace, gets a bit of turn. I'd actually say he's only marginally worse than Ojha, Mishra or Ashwin. And he's the youngest of the lot. With more time and FC cricket, and a good captain/coach who knows how to use spinners, he can be developed into a very useful bowler. He's got all the raw ingredients. He even bowls a good armball. He needs time and experience.
His batting will never be good enough to be in India's Top 6 in Test Cricket or ODIs, and he isn't a natural lower order hitter. So either he works on his big hitting ability, or we play him in the top order despite having better choices.
He's proved in his international and domestic career so far that he has the temperment and ability to play big innings and work the ball around. In domestic cricket and in the IPL he's was and is used as a top order batsman around whom the innings is built.
The latter is always going to be an issue with Jadeja. Fitting him in the side will be hard.
And the problem with his bowling arose because a) He was picked for the World T20 with no cricket behind him and b) He was persisted with despite being out of form.
Naturally he got a lot of stick in the World T20, due to being out of practice, and that affected his confidence. Repeatedly playing him meant his confidence and form kept falling, and his bowling became flat and ineffective and predictable, to complete garbage.
Very much like what is happening to Johnson.
It doesn't mean Jadeja isn't talented. He is still our best allrounder prospect, or atleast one of the best. He just shouldn't be anywhere near the side now. Needs more time in domestic cricket to get back to his old form.
For this WC, if Irfan is fit and in form, he should be picked. If not, we can go in with Harbhajan, 3 seamers (without Ishant, please), Dhoni and 6 batsmen. Yuvi, Raina, Viru offering part time spin.