It never ceases to amaze me why managers decide to change the formation of their team or sections of their team purely for the sake of change without any discernible logic for what they are doing.
The best display of attacking football in Ulster this year had been given by Armagh when they decisively beat Down in their opening-round game -- with Billy Joe Padden playing a vital role at centre-half-forward and scoring three points from play.
But yesterday, when Armagh lined out to play Derry, they pushed Padden much further forward, almost into the full-forward line, and this seemed to completely disorientate the whole attack, if not the entire team.
Another casualty of this ill-advised tactic was Jamie Clarke, touted last week by Joe Kernan as the next Colm Cooper. But he was practically invisible for most of this game because of Armagh's inability to get any decent ball into him. He scored a solitary point.
Derry quickly aggravated Armagh's problems by dominating the midfield tussles, through the massive Joe Diver and Michael Friel, with additional assistance from Enda Muldoon operating largely as a spare midfielder. With limited ball supply the Armagh attack was only a pale shadow of what it had been against Down and it was no surprise that at half-time the score was Derry 1-8, Armagh 0-6.
But when Michael O'Rourke stormed through the Derry back-line straight from the throw-in and rocketed a shot into the net, I thought maybe Armagh had learnt their lesson.
It was all in vain however -- even though they only trailed by two points -- because Derry strengthened their grip on this often fascinating game as the second half wore on.
Sometimes in big games, the smallest things tell us the most about a team's attitude. Just after O'Rourke's goal we saw a classic example of that.
He had barely returned to his position in the half-forward line when his marker Charlie Kielt won possession and charged 50 yards down the field to score a magnificent point. It largely undid the psychological damage of that early goal.
Within about 10 minutes Derry were seven points ahead and the promised Armagh revival turned out to be a myth.
Armagh were torn to shreds often through their own self-destructive tactics.
Why they failed to switch Andy Mallon -- a brilliant man-marker for years -- onto the rampaging Eoin Bradley earlier is the biggest question the Armagh brains trust will have to answer as well as the mis-management of Padden.
The younger Bradley, possibly freed from the pressure of playing second fiddle to famous brother Paddy, played like never before and was the star of the show.
It was interesting to contrast the three substitutions made by the respective mentors regarding forward lines.
Armagh took off O'Rourke, Padden and Tony Kernan in desperation and in rapid succession in the second half, while Derry could afford the luxury of taking off possibly their three best forwards -- Bradley, Martin Lynch and Muldoon -- in the last 10 minutes.
That sums up the relative worth of these two teams on this day at least.
This was a game full of excitement, drama, wonderful goals and many great points. It was very sporting and generally a great advertisement of open, positive football. The pity was that only about 15,000 fans turned up -- the Derry turnout in particular was pathetic.
This was a very important victory for Derry, who had lost their last seven Ulster semi-finals but can now plan with purpose to regain that title. But with Derry footballers there is usually a caveat -- their inconsistency.
They have a notorious record of being very good one day and flopping the next so their approach to the Ulster final will be crucial if they want to make the progress that their performance in Clones deserves.
They have a big, powerful team with massive physical strength and football ability.
At midfield Diver and Friel shone with able assistance from the talented and long-serving Muldoon. It was the Ballinderry veteran who set up the first goal for Martin Lynch.
It is probably hasty to judge the excellent performance of the Derry backline -- who kept Armagh to six scores from play -- on this one performance. But a different attacking formation from Donegal or Tyrone will be needed to see if the Oak Leaf rearguard is actually as good as it looked.
Armagh will be shattered after this performance. They were caught on the hop by Derry's performance and game plan -- but must stand indicted from their failure to take counter measures and for not making the best use of their starting players.
Instead of building on the solid result they got against Down, they tried to be too clever with unnecessary switches and only succeeded in confusing themselves and making life much easier for Derry.
They will find it hard to make an impact in the qualifiers following this comprehensive defeat -- which was never a possibility as far as Armagh's mentors, players and fans were concerned.