Friday 13th has meaning for a lot of people.

For me it’s the date when, following much debate, I finally got around to documenting my thoughts on the Szczesny-Ospina conundrum.

I examined a number of aspects a goalkeeper must excel in to be considered good enough at the top level, and I compared our two main shotstoppers on those criteria.

One man came out head and shoulders above the other, and I was categorical that he should come back into the team. I may not be so very good at predicting scorelines, but when it came to deciding which of our two keepers should have their name tattooed onto the team sheet, the evidence was there for all to see.

Many argued.

Wojciech Szczesny seems to be marmite for a lot of people, either they love him or hate him, and those that argued did so on the basis that the Pole had made numerous mistakes this season while his rival had not.

At the time, I felt that those mistakes were just a bit less high profile.

In any case, the argument that he hasn’t made any mistakes no longer stands.

TWO WEEKS IS A LONG TIME IN FOOTBALL

In the two weeks since the original column, Arsenal have played three games.

Szczesny kept goal in the FA Cup against Middlesbrough while Ospina was in nets for the League clash with Crystal Palace and, of course, the Champions League humiliation against Monaco.

One argument that seems to be the bedrock of those who prefer Ospina in goal is his number of clean sheets and goals conceded. The small matter of sample size or quality of opposition appears not to matter.

So to continue with as the that basis of analysis, for the past three games Szczesny, with his 100% clean sheet record and 0 goals conceded, would now be ahead, while Ospina’s four goals conceded without a single clean sheet is more than a blot on his copybook.

As with before, stats can only take you so far.

But since we’re looking at stats, here’s a few more.

Against Palace Ospina faced just three shots on target, two straight at him from central areas, and conceded the only one which was not.

Against Monaco, he faced seven shots on goal, conceding three of them despite half of Monaco’s shots originating from outside the area.

Meanwhile Szczesny saved Boro’s only shot on target, giving him a stunning save ratio of 100%.

Cold hard evidence that the Pole should be back in goal…no?

Of course I’m being more than a touch facetious. Taking a sample size of three games is hardly representative, especially when one of those games is against lower league opposition, yet previous judgments on Ospina were passed with just six games under his belt.

So then let’s take a slightly less quantitative look at Ospina and focus on some of the clues which show just why Szczesny’s return is an absolute no-brainer.

ALARM BELLS

Let’s start with the Crystal Palace game.

Arsenal take a two goal lead but need to stay alert at the back. A 2-0 lead is widely regarded as a very dangerous position as a single goal will give the home side the incentive to really go for it with momentum fully behind them.

At that point, it becomes vital to have consistency, of course, but it also means we need to look to our goalkeeper to snuff out any threats and dampen the Palace spirits.

What we don’t need is the goalkeeper to charge out of his area and to just about make contact with a headed clearance before clattering into his own player.

I’ve long bemoaned Ospina’s unwillingness to do the sweeper-keeping, but on this showing it looks like he’s not terribly suited to it. It was not an isolated incident either.

Recall the moment in the Leicester game where he charged out wide to the left winger, leaving the freedom of the penalty box to whomever cared to arrive. It was pretty much a carbon copy of the first goal Szczesny conceded at Southampton, except for the one minor difference that this time the attacking side didn’t take advantage.

In my book, it doesn’t make the decision or the mistake any better just because the opposition failed to exact consequences.

But sweeping up behind the defence wasn’t the only weakness of our Colombian stopper exposed by the Palace game.

As a side that focussed its play throughout the game around wingers and crossing, and then brought on a ginormous lump in the shape of Glenn Murray, it was fairly obvious what their gameplan would be in the final ten minutes – get it in the box and let the carnage unfold.

And lo! Carnage was what unfolded.

It was exactly the same approach taken by West Ham over the festive period when Kevin Nolan was sent on with quarter of an hour to go to support Andy Carroll. However, where Szczesny put himself out there to dominate his box, Ospina chose instead to remain close to his goalline, and rely heavily on his defenders to clear the aerial threat. That the post alone saved us from dropping points is evidence that this approach isn’t suitable.

Height isn’t the be all and end all, but for a goalkeeper, those five extra inches Szczesny (6’5″) has on Ospina (6’0″) can make all the difference. As someone of “diminutive stature” myself, it is hugely irritating that height, a factor you have no control of, can be the difference between the level that you can play at.

However it is unfortunately a fact of life and, for me, it’s why Ospina will always be limited at the very top level by his size.

DEATH KNELL

Fast forward to the Monaco game and it’s possible that his size again played a part, albeit this time in relation to the shorter reach that inevitably corresponds to the extra few inches of height.

Per Mertesacker might take some heat off our Colombian keeper as the villain of the night, but Ospina was definitely doing a passable impression of being his trusty sidekick.

Of the three goals, Ospina simply had to do better on at least two of them, and there was one moment that summed his recent performances up for me really.

Mertesacker and Koscielny had an awkward exchange of passes rather than taking the safe option to clear, and after inviting pressure on they ended up pushing it back to the keeper.

You’re thinking ‘just get rid’, as quickly and as far away as possible. Literally, anywhere will do, as long as it’s out of our half.

I presume that’s what Ospina tried to do, since he surely can’t have been intending to do what he ultimately executed – a scooped lob of a clearance which landed less than five metres from the edge of the box and still fairly central.

On that occasion we got away with the mistake, but we were not so lucky in the 38th or 94th minute. Of course the defence should do better, that goes without saying but, ultimately, your goalkeeper is in the team to back the defence up when they do get beaten.

For the first goal there seems to be an eternity between Kondogbia striking the ball and it glancing off Per Mertesacker, and then yet more time between that moment and it looping past Ospina. A vicious deflection is one thing, but the trajectory of the ball both before and after it hit Per wasn’t exactly towards the corner of the goal.

Ospina isn’t “set” or committed to either direction at any point, he just fails to react.

I’d love to know what the “shot clock” would tell us about the time from strike to goal.

In any case, even if he doesn’t end up getting there, he really has to at least make an effort – the failure to move any part of his body in an attempt at saving the shot is terrible. He has to do better (the former pro goalkeeper I live with agrees on both counts, in case you wondered).

Let’s skip straight over the second goal as the less said about that the better really, and look at the calamity of errors that led to the third.

I’ve already written about Per Mertesacker’s complicity in this one, but Ospina simply has to do better with the save. I talked earlier about how height or size can make all the difference at the top level. Whichever way you cut it, the Colombian couldn’t make that difference in this situation.

You can either criticise the weakness of the hand he did get to the ball, arguing that he should have made stronger contact to push it around the post, or you can return to the point that an extra inch in reach would have meant that for a taller keeper it could be a more comfortable save, and one that would have kept us in the tie.

The first is something he can improve, the second is not. For me, Szczesny’s extra size could have been the key factor in that moment and it’s why I see him, not only as a more accomplished keeper for the present, but one with the potential to be completely top drawer with a few tweaks to his game.

In pressure situations, you need every player to be strong, to be reliable and ultimately to deliver.

There was a level of panic in the Arsenal defence that wouldn’t have been there with the right confident leadership at the back, and that is driven by the captain and the goalkeeper.

Both were found wanting, and as a result there have to be questions over whether either should be involved at the weekend.

TIME FOR SZCZ-SZCZ-SZCZ-SZCZ-SZCHANGES

We’ll probably never know the full ins and outs of why Szczesny was dropped this season – it certainly appears to be more than just form related  – but no doubt a couple of high profile errors made the decision that little bit easier.

So if the Pole was dropped on the basis of making mistakes then it seems natural to me that the same should be true for Ospina following the week he has just had.

As I alluded to in the original column, Ospina’s mistakes are not as high profile, simply because his game revolves much more around playing it safe, but they are mistakes nonetheless.

It’s a source of great frustration to me that we have had to wait for him to make those mistakes in a critical Champions League game before we reach the point of dropping him, despite all the warning signs.

Of course that rather assumes we do indeed actually drop him – let’s hope so!

Most managers like to do a little rotation with their keepers to keep them on their toes and make sure they’re fresh and ready should they be called upon – that’s fine in cup games – but when it gets to the business end of the season, you want your best option playing every game they can.

Szczesny is unquestionably our best keeper, and he simply must return at the weekend.

I want my number one back. Now, Arsene!

@nellypop13