There are not 2 roles in this game there are 3.
Offense, Defense and Support.
The first two are obvious, the third is not so understood.
The support role is a role that can be played ny players that do not have more than 4 hours a day to sit on the game and play.
When I started playing Travian, I was on extended leave with a back injury. I was on here all day every day for over a year and yes I did well with the alliances I joined.
Since then I have mainly been in work and have a family. I find that my game time is limited to 2 - 4 hours a night, sometimes even less. Does that make me a playe that cannot be of any use ? No.
In my last game, Server 1, I started out late in the game and had been made redundant at the time so I started well. Then I got a job and my time was limited. I offered to drop out of the game. Luckily Oscar of Reborn said Stay, just do what you can. So I became a troop hotel, a supplier of resourses, a dive in when I had the chance player. For me it was perfect, and although we did not win our alliance were in top 4 at the end of the game. Would I have prefered to win ? Of course. We all play to win, but in these games the journey and friends that you make on the way to the final WW takeover is as much part of the fun as the final result.
I know there are Die Hards out there that will insist you have to be on 28 hours a day and must take part in every action, and yes they sometimes win. The fact is though that any alliance can win, even with Support players on their team. These are the people that stop troops from starving, home excess troops when your Village City can no longer hold all of the troops you want to have but cannot feed, and various other tasks, including Battles, Defense etc.
Thats my 2 pence worth. I am sure there will be many views on this and many that will not agree, but having played this way and succeeded with top alliances I can say that yes it works and for players who are limited on time, carry on playing, explain your time constraints to the allaince and tell them what you CAN offer not what you cant.