Here is my two cents..
2-3 years ago, can't remember exactly, i went to a physio as i had shoulder pain for about 4-5 years that was getting worse...i could bowl fine without any pain but everytime while fielding when i threw the ball i would feel a lot of pain, it got worse near the end where it would be constant pain even while i sat stationary...
So physio did his work and told be there was a muscle near the right shoulder blade was weak and because of that the shoulder joint was not supported properly so certain movements made the shoulder move more than it should causing pain...regardless the rubber tubing was great for those workouts and acutally helped strenghten the muscle and pain slowly went away...
it did not make be bowl faster though,,,my pace has increased over the last coupld of seasons but i credit other things for it...
1 - I play badminton a lot and have a powerful smash, i practise with my friend for hours where i would smash one and he would return it, then i lob it up and he smahses, we do this a long time atleast once a week during off-season,,,plus then we play with other for abt 2-3 hrs once a week...this is find is great as its a burst of enerrgy then a second or 2 to between the next one...
2 - Lots of cardio increases your stamina, which means you can run in harder consistently, i also found i lost weight due to walking a lot which made me move eashier and faster...i am not one of thise runners but i do walk a lot, tu the tune of 40-50 KMs / week
overall this winter i have been lazy / busy and can already feel i am slower in the nets, thats what works for me may not be for everyone...rubber tubing will help with making muscle stronger but will not make you faster...