Since apparently I had posted too much data here and I cannot expect that everybody has time enough to spare reading many reports and looking at many pictures, now I will compare only 2 battles with worms - 16 days ago and today. In both cases I fought with ABSOLUTELY THE SAME group of worms - 2 big, 1 medium and 1 small. To make things easier I give summary report for comparison between my army in the battle before and in today's battle
1. https://drive.google.com/file/d/0B63EjveXN5tPR1JkMlZ6STlkSGM/view?usp=sharing
For those that doubt here are screenshots of the two battles
2. https://drive.google.com/file/d/0B63EjveXN5tPZi1paWN1X1lEVWs/view?usp=sharing
3. https://drive.google.com/file/d/0B63EjveXN5tPcndrUHlKSWJTTzg/view?usp=sharing
Comparing the 2 battles, the result is - 9 units lost in the first battle, 14 units lost in the second
There are the following differences in army and hero strength between the 2 battles:
HERO STRENGTH: hero lvl 27 in the first, hero lvl 28 in the second
ARMY STRENGTH: after hero leveling up I used the skill points to increase Army defense and Hero strength for the second battle. Army was increased in number by 33 units - details in the first link
ARMY STUFF: The major difference in army stuff are the 5 battering rams that took part in the first battle and didn't take part in the second one. Battering rams by definition don't fight with land units, they are used against enemy fortification. Since I have tracked all detailed reports of battles where there are battering rams, and didn't see that they suffer hits or deliver hits to the monsters, I decided not to roll them back and forth and for the second battle left them behind. There is 1 monkey and 1 explorer more in the army for the first battle, but I don't think they are the forces that make the serious difference.
If I can sum up the results - after increasing army defense and number, hero level and strength my losses in the second battle are 64% more than before. If my army was absolutely the same in number and strength as in the first battle, my losses in the second battle should be much more - more than double as was shown in the previous examples.
The possible reasons for such a result, in my opinion, can be:
1. When Hero levels up, he/she or the army becomes less powerful against worms - for me this doesn't make sense at all.
2. The different types of worms - small, medium and big - have more strength than 16 days ago. If so devs should inform us, because when I click on a worm, it has the same HP as before.
3. Despite that they are siege weapons, the battering rams somehow are calculated or in fact take part in a battle with worms - if so, then the detailed battle reports are wrong. (I do not even try to discuss one monkey and one explorer as a factor.)
4. There is some unknown factor in the battles - if so, i wonder how someone can create an effective strategy at all.
From my experience until 2 weeks ago I could tell that more ballistas and archers accompanied by enough units like centurions, legionaires, braves and cavemen to defend them from worms and to serve as cannon meat is enough for a battle with not too much losses, but this is no longer true
If somebody can see a factor that influences the battle with worms which I have missed, I am open to suggestions. Or to an explanation why at present I have more lost units than before.