You are right . If the bowling action is flawless . then the chances of getting injure are much less . Again , not all players fitness is the same . Some players fitness is good ,again some players fitness is average level . They have to working hard for better fitness .Many potential players have ended their careers due to fitness issue and injuries.
Javagal Srinath was the backbone of Indian pace attack during the 1990s. When he was at his peak, a rotator-cuff injury forced him out of playing for almost a year (in 1997). His team-mates such as Venkatesh Prasad, Debashish Mohanty and Ajit Agarkar also faced frequent injury outages. However, during the last two decades, such incidents among Indian bowlers have remained rare. Players such as Zaheer Khan, Munaf Patel and Irfan Pathan missed very few matches due to injury.