Suspect that Lybushkin didn’t arrive to camp in shape.
Possible. Usually, within the first couple of days of camp, a conditioning test is done, in addition to all of the normal measurements. I recall that in my lacrosse days, the requirement was that you had to run 4 gassers, which consisted of a lap around the field within a certain time frame, with periods of rest in between. The first and second ones were easy - it was the 3rd and 4th where you were able to see who was:
a) really in shape
b) in shape, but not necessarily exceeding expectations
c) out of shape
I can imagine that every year, about 10-15% of rosters have someone falling into categories B and C. Whether it was self-inflicted (player's fault for not paying attention to the program) or an issue because of late season surgery that prevents someone from skating/movement until close to the start of camp is where coaches and the training staff make decisions about where a player is at. Remember, it can take up to 4 months to get into shape, especially if no activity is done. Probably closer to 3 months, which is why you see players taking the month of May off if not in postseason, and usually are right back into it June 1st. This way, you are ready to go for camp if you are pushing yourself. Most people don't know how to push themselves past their limits, though, unless training with others.