I see it year in and year out where players return to off season training in terrible shape. Way worse then where they left the previous season. To me this is completely the wrong approach. Sure, after a long season you want a rest but it doesn't take very long to recover, a week maximum. After that you should get back in the gym and start working on your limitations and building a base for the heavy lifting that is to come.
I don't run my athletes in this time frame as they tend to do a lot when they get back to training and I find it is the running that breaks them down the most and drains them the most mentally. If they need to improve their conditioning then I do it in the gym and use modified strongman training. It is only as the off season approaches where I may add in some interval work to prepare them for the running ahead. But this is for a very short period of time and the sessions are short.
A good recent example of this is Christian Urso. He is back at training this week with his team and had to run a 2km time trial (why we still run 2km time trials is beyond me but that is a rant for another time). He got it in 8:29, which is a decent time (best I know of in league is Beau Ryan with about a 7:10), and he did not run at all in the break. He just done weights. He has also added 4kg of body weight in the break. He has set himself up for success. I think he will break the 8 minute mark next time they do this.
Strength is the biggest limitation for most of the league players I see. The majority of the time this is due to injuries that have occurred due to horrible lifting technique and muscle weaknesses/imbalances that have been unaddressed for a number of years. I have seen many players who have been in junior development programs and even NRL full-time squads that cannot squat, deadlift, or chin, yet day one they will be tested on these lifts and then they will make up a large component of the training program. No one addresses the weak hamstrings, lower back, VMO, etc. nothing. It just continues on year after year. You have to take it upon yourself at times to seek out those that can help you in your own time fill in the missing links so you can end up surpassing where you are currently at.
The other thing is nutrition. Most of the time the diet tends to be poor anyway but come off season it is completely thrown out of the window. Just having a good nutrition plan can save you from doing a lot of extra training that is wasting your time and energy. They try to out train their poor diet and all the alcohol they drink in the break. Have some fun but don't ruin yourself. Also if you are sloppy and your club has been trying to get you to lose body fat and you end up going back in better shape then you left them, then don't you think this will make a good impression and perhaps change people's perception of you? As a young bloke or someone on the fringe of NRL, these things can make a big difference. It could be the difference between getting a contract or not, or whether you start in the NRL or reserve grade.
You don't have to be at your peak day 1 of training but you shouldn't be that far off it. If you maintain in the break it sets you up to take your game to a whole new level. Instead of just getting back to decent level of physical preparedness you can increase it, but you can also focus on skill components instead of having to do extra work on conditioning for example.
Let's say you are a young league player and you back squat say 100kg year one by then end of your off-season and during the season that drops to say 90kg, the following off season you want to be able to take this to 110-120kg, by the end of the year you may drop to 100kg, the following year you go to 120-130kg, this may drop to 110kg. Then you come back and drive that number up to 130-140kg, and so on. That is how you make continual progress each year.
After the season you build yourself back up with some general exercises, working on your current weaknesses, injuries, and areas you need to address. This then sets you up for the heavier work to come. It isn't that taxing on the body. You aren't doing a whole lot of volume and the intensity isn't very high either. Obviously if you hadn't played many games that year and weren't too beat up then you could adjust the amount of work you do.
You are an athlete, not a normal person, so behave like it. There are sacrifices to be made. Some guys can do nothing in the off-season and come back to training fine. They are very rare and more than likely this isn't you. It definitely isn't me. And if it were you or me we'd know it as we would probably be playing for Australia and have a couple hundred NRL games under our belt. If not, then get to work.