Catch it! Catch it! .... Catch it!

There'll be short posts as well as long posts.
So, in cricket, right, I generally stand by modern coaching decisions and believe they've analysed things carefully, and that standard policy, though sometimes counter-intuitive, is overwhelmingly the right decision e.g. in limited overs, taking your batting powerplay late, e.g. safe rather than daring declarations e.g. no third man e.g. six batsmen, four bowlers.
But here's a thing. When I played cricket, and a ball came in the air towards me, the last thing I wanted to hear was some overexcited team-mate shouting "Catch it!!!!" Yes, I know, it's in the air, coming towards me, i recognise the positive effect catching it will have on my team's situation, I don't need you to prepare me for that situation. All you're doing is putting me off, tightening my muscles. If i catch it, I wil be able to excuse your enervating cry as over-enthusiasm, if i drop it, i will hold it against you for the rest of my life.
And yet. They still do it. Every time. In test cricket. It goes in the air. Matt Prior, or Graeme Swann, or whoever shouts "Catch it!!!!". Do the scientific statistical tests prove this is a policy that works, that sharpens the catcher's senses to improve the possibility of success, or is it just uncurbed immature anxiousness? And if so, come on Andy Flower, tell them to put a sock in it.