The astrological explanation is very simple: He has Shani-Mangal yuti in his horoscope in Kanya rashi. Shani with Mangal does show injuries and inconsistency from time to time (Inzamam Ul Haq one more example).
From Sept 2009, Shani entered Kanya (Virgo) and it is on his horoscope Shani-Mangal. Not the best period for any player. This Shani is also aspecting his Chandra-Raahu yuti (highly temperamental and arrogant yuti) which is testing his temperament QUITE a bit. ONLY way out of PATIENCE and HARD-WORK!!
Of course, GURU changing from May 1st, 2010 WILL CERTAINLY Help Yuvi. He should give MUCH better performance than the IPL 2010. This Guru in Meen raashi will aspect his Mangal Shani and should reduce the intensity of Shani's travel there. Again, Shani's travel does recommend shraddha, saboori and hard work anyways! But this Guru should help him quite a bit.
I am looking forward to some outbursts from Yuvi, from his BAT that is...Aren't you??