The 25-year-old scored 142 in England's victory over Sri Lanka in the second Test at Edgbaston, taking Pietersen into the International Cricket Council's top 10 batting rankings.
Since breaking into the England team for the victorious Ashes series last year, Pietersen has average more than 50 in his first 13 Tests, including four centuries.
That aggressive style of batting, which has already helped him hit 27 sixes to put him fifth on the England list of Test big-hitters, has led to some critics labelling him as nothing more than a slogger.
But Fletcher claims it is his attention to detail that serves him so well.
"I just think he's a very exciting player," said Fletcher.
"He's new to Test cricket and he's done very, very well. He is exciting and I find him a very clever cricketer. People think he just goes out there and just plays the game, but he really thinks what he's going to do.
"He doesn't go out there and just play by instinct. Some shots maybe, but generally he's got a good plan of how he's going to play every bowler."
That was underlined in the last Test when Pietersen referred to the video footage available in the dressing room of sling-shot style fast bowler Lasith Malinga before deciding on an effective game-plan.
Malinga hit him in the stomach during his brilliant century but Pietersen generally dominated all the bowlers - including prolific off-spinner Muttiah Muralitharan.
"He really thinks his game out and added to that he's got some real talent," added Fletcher.
Pietersen will become the first England player in history to score centuries in four successive home Tests if he follows his hundreds against Australia at the Oval last summer and the two against Sri Lanka this summer with another in the final Test at Trent Bridge this week.
He is already the 12th player in Test history to record the triple and the sixth England player to achieve the feat, but if he also succeeds at Trent Bridge he will be making new ground.
South African-born Pietersen, who had to complete a three-year qualification period with Nottinghamshire before he could play for England, has already made an impact on Test cricket records in his short space of time playing international cricket.
He has the second highest strike-rate in the modern game of 70 runs per hundred balls, a figure only bettered by the 74 of India's Virenda Sehwag, while only Australia's Clem Hill (70) has a similar strike rate in the history of cricket.
Pietersen is certainly continuing in that style during the current series with Sri Lanka - he has a strike rate of 80 while no other batsman has managed to rise above a rate of 56.