I think the issue is that playing online and playing offline is 2 different experiences or playstyles. With how the stamina and speed is set up as more simulation compared to arcade. So in a sense you have a rush or 2 at most and then dump the puck for a change or use goalie stoppages to change lines (following this there is no real issue with stamina). The stamina will stagger out across them and always leave you with one full or almost full line (forward and defense) to use with the others staggered from 50% or so, 25% and one less (all depending on how long the players are on the ice for).
The real issue from my experience online is most don't play a more traditional style/experience of hockey and is more fast paced + less stoppages. This is where the issue lies cause prior games like 23 and 24 were catered more to the arcade style where stamina and speed were OP compared to real life, where you didn't need to hold the puck on a goalie save and just throw it out and keep playing due the higher stamina. You could also use the speed burst almost constantly and blow by defenders due to this, with little affect on stamina.
It's hard to find a balance between the 2 as its style of game differs to drastically from online to offline - its hard to almost impossible to find a good balance.