I don`t see them making a huge difference to be honest with you. Kulasekhara with the old ball will be cannon fodder with his pace and Tushara has played against India before with very limited success. These Indian batsman scored tons of runs against better bowling attacks of
Australia (Lee,Clark,Johnson,Siddle) and England(Harmisson?,Flintoff, Anderson,Swann,Broad) just last year. Those are argualbly better or at least more seasoned pace bowlers than Tushara and Kulasekhara. That does not mean Kulasekhara and Tushara cannot take wickets but its highl unlikely they`d have done any better than Welegedara did at Ahmedabad.
Its Murali not picking up wickets which is a bigger problem for them. I still don`t know why they dropped Kulasekhara.