Here is how your sentences read to me, if you try to get to the deeper level.
1) Since/because I am a cricket player, (that is why) I have to practice every day to be fit.
The first part of the sentence is the explanation of the second part. It's the reason you do the next part.
2) I have to (practice being a cricket player every day) to be fit.
Here it sounds like the only possible way for you to be fit is by practicing being a cricket player every day.
So, to get to the point of your comma question, in sentence 1, the introductory phrase is incomplete by itself, and takes a comma to show its connectedness with the second part, where you tell me what it is I need to know about your being a cricketer. "Being a cricketer" is not a sentence alone and I know to expect more to come.
In the second sentence, the whole entire phrase in parentheses above is functioning as one element. It could just as easily be replaced by run/swim/throw a discus/do 100 one-handed push-ups, but it completes the idea that is begun with the "to" in "I have to_______."
I think the clumsiness of the second sentence comes from the order in which the information is presented. Your first sentence gives you some info, takes a breath, and explains why it was shared. The second just starts jamming everything in, a feeling which mostly comes from, possibly, the time info (every day) being put in between the "to" and the "_____" mentioned above. "I have to every day run/ I have to every day swim" just aren't constructions typically used. (and to make it more confusing, would probably typically be set off by commas "I have to, every day, run) So, a more natural placement would read "I have to practice being a cricket player every day to be fit."
Commas were always explained to me as places to pause, which is probably why I put them all over the place, most likely incorrectly. But, if you can pare down your sentences to their basic elements and see how they fit together as bits and pieces, or put in other, similar words and try them out, you'll usually be fine.
Short answer is, introductory phrase takes a comma. Verb phrase doesn't.