It's not that poor, Gerd. Consider that Arsenal plays almost every week and international friendlies (or qualifiers) only happen once in a while. Yet if we observe the ratio of injuries by each case, I have a clear impression that the number of injuries in international duty is alarmingly high.
To add insult to injury (pun intended

), those latest matches were friendlies.
I have bad memories of Van Persie coming back crocked from duty with Holland and spending 4 months out (has happened a few times) and that especially irritating story of Didier Deschamps calling on Abou Diaby for France, when he had only been fit for a few weeks after the usual Diabyesque period of 10-12 months. At that time, Wenger had warned FFF he was not ready, but they used him anyway and guess what... another setback in Diaby's recovery.
Furthermore, physios at the National Teams are not always are up to speed with fitness issues of players. To be fair, it's a lot of data to consider.
Of course it's a good thing that the players at your club are good, which means they are called to represent their country. But at the end of the day, most football fans feel aggrieved when their players come back injured, also in the knowledge that it is the club that pays their wages, not the federations.
I think accidents happen, it's fine, but I what also plays a big part in this is the big pressure some players are under to show the National Team managers that they deserve a spot in the first XI. You see, Jack Wilshere played through pain for 60 minutes against Denmark. The player wants to play and earn the manager's trust, but at the end of the day it is still a bloody friendly and he could have aggravated his injury.