I think Arsenal, Aston Villa, and Tottenham have the same big chance of getting tickets to the Champions League next season because all three have performances that I think are at an equal level for now. So it is quite difficult to predict which one of the three teams will come out of the top 4. It is likely that the factors that will determine who will remain in the top 4 when the season ends are good strategies and solutions when dealing with injury and fatigue.
The competition to get the champions league zone next season is very tense and these 3 teams both don't want to lose in winning that place. Maybe now it is clear that Liverpool and Manchester City are the top two teams that have managed to secure the Champions League zone and now the remaining two are up for grabs. It is not certain that Arsenal will be safe considering that this season is much more difficult with Aston Villa breaking into the top flight and Spurs may not be able to move freely because this season is still an improvement after last season they were unable to secure a place in the Champions League.
Maybe it's true that strategy and preventing players from getting injured are two things that can't be separated if you want to remain consistent, but I don't think it's easy considering the busy schedule that a team that is still active in other European competitions will have to go through. In this case, Arsenal is a quite busy team because they have to divide their schedule with the EPL and Champions League.