The beauty of football is that for 99% of the time it is a player's game. Yes, the coach picks the team but once they step over the white line and the referee blows his whistle, the man in the technical area is pretty much powerless to affect the play.

Sure, instructions can be yelled but over the noise of 50,000, they're rarely heard. Of course, positions can be swapped but there's no calling for a time-out and diagramming movement on a clipboard. To really try and change a match, coaches have to wait until that 15-minute break at half-time.

Let's now discuss the 1% area that the coaches can change during the course of a match...and that is substitutions.

Yesterday, a Scotsman, Englishman, Italian and a Frenchman all had the opportunity to use three players each to turn the Manchester-North London double bill on its head. The success or failure of these respective moves can only be judged in one way...by points.

Of course some changes are forced as in the case of Sir Alex Ferguson who had no option but to replace Phil Jones or Nani once the United players became injured. Other changes though are made to hopefully impact the match in a positive fashion.

In the early match between Manchester City and Tottenham, the Italian, Roberto Mancini, decided that the 65th minute was the time to use one of his trump cards - Mario Balotelli. After throwing away a two-goal lead against the north Londoners, you couldn't help but feel his frustration as three points seemingly slipped away.

Now, I'm telling you that there is something really freaky about the timing of this substitution. Either Mancini is the luckiest man in the world or he has some weird karma looking over him.

Against Liverpool in November at exactly the same time in the match he introduced this explosive raw talent. Eighteen minutes later the explosion was back in the showers after leaving an elbow on Martin Skrtel.

Sunday, Balotelli had been on the pitch, yes, you've guessed it, 18 minutes, when he decided to backheel Scotty Parker's head. How Howard Webb, the referee of the 2010 World Cup final missed this cowardly act of violence is a mystery to me, but I'm sure he's moved a notch higher on Mancini's exclusive list for a nice expensive dinner.

So instead of being down to 10 players, City remain with their full complement and Mario is on the pitch in the 94th minute to not only win a penalty after Ledley King's clumsy tackle but to take the spot kick himself and keep the Mancunians on top of the table in a heartstopping 3-2 win.

Mancini, thanks to the generosity of Webb, has made a substitution of sheer genius. Unfortunately in this case, if there is a genius, there also has to be a buffoon. Please step forward Frenchman Arsene Wenger.

After watching his Arsenal side get outplayed in almost every department against Manchester United in the late Sunday match at the Emirates, his bold move of starting inexperienced teenager Alex Oxlade-Chamberlain actually looked like a minor stroke of genius...and then!

No sooner had Oxlade-Chamberlain provided the 74th minute equalizer for Robin van Persie than Wenger decides that that is enough and substitutes the one player who had looked consistently dangerous with, and I use this term lightly, a player who has no right to pull on the red shirt of Arsenal - Andrey Arshavin.

For the past two seasons, Arshavin has looked like a player that has no interest in playing football in London anymore and his first contribution of note was to help Antonio Valencia, United and Danny Welbeck find a winner.

The most telling part of this bungled substitution was the reaction of Arsenal captain Van Persie. Just as the chage was taking place RVP mouthed "no" in the direction of Wenger as the number of Oxlade-Chamberlain was held up.

I have no doubt that this change cost Arsenal the match, although Wenger, in his post-match comments, had a different take.

"Oxlade-Chamberlain had started to fatigue, started to stretch his calf, and was not used to the intensity. He was sick during the week. Arshavin is captain of the Russia national team. I have to justify [substituting] a guy of 18 who's playing his second or third game?

"Let's be serious. I have to stand up for the substitutions I made. I've been 30 years in this job and have made 50,000 substitutions and I have to justify every time I make a decision? I do not have to explain to you every single decision I make."

Arsene, this time you do. You got it wrong and probably just cost the club Uefa Champions League football next season.

As Wenger rightly pointed out though, he has made 50,000 subs in his career and over the course of a campaign who really remembers who comes in and who goes out? I'm pretty sure that come May we might cast our minds back to late January and the two changes that may have altered the course of this season in more ways than we can imagine.