While they only narrowly missed out on the top four last season, the collapse towards the end of the season suggests it's not hard to argue that Arsenal need to invest in the squad if they want to avoid another disappointing season in the Premier League and abroad.

It’s been a disappointing period for the Gunners of late. A domestic slump saw them win just one of their remaining five games and drop into the Europa League places behind close rivals Spurs and Chelsea. And in Europe, Maurizio Sarri’s men ran rampant in Baku, leaving travelling fans in a state of utter dejection and ruin.

Emery must get this summer right regardless of the relatively (per talkSPORT) minuscule £40million budget handed to him. To put Arsenal's budget into context, Manchester United are working with an estimated £250million (per the Times via the Manchester Evening News). That surely means the Gunners need to prioritise signing reinforcements for the club’s most vulnerable positions, i.e. defence.

Arsenal completed the season with the worst defensive record in the top five, conceding 54 goals in total. That’s 12 more than Tottenham and Chelsea, and 29 more than Liverpool – the staunchest defenders in the league. Good enough? Absolutely not.

Recent reports from the Daily Mail linking the Gunners to Celtic left-back Kieran Tierney is a real step in the right direction, should a bid materialise. The 22-year-old Scotland international has been turning out for the treble treble winners since 2015-16 and would at least inject some fresh ability into a left-back position that is currently occupied by an ageing Nacho Monreal and Sead Kolasinac.

With Tierney’s transfer in mind, we’re going to discuss three possible knock-on effects if he joins Arsenal in the summer…

Gunners sell either Monreal or Kolasinac

Perhaps it'd be a case of one in, one out.

Due to their apparent financial shortcomings, Arsenal might not have the luxury of holding onto three players in one position. Especially when one of them is 33-years-old and moving towards the natural end of his Emirates career in the form of Nacho Monreal.

It currently seems unlikely that Arsenal would cash in on Kolasinac, despite rumours suggesting (as per Mundo Deportivo) that Emery would be prepared to sell the Bosnian to Barcelona, given he’s got years left in the tank, but perhaps the budget concern would push him towards such an exit if Tierney did indeed arrive .

Arsenal bag a future star

The 22-year-old has been on the radar of a number of clubs for some years now (linked with the likes of Liverpool by the Daily Express back in 2015), having progressed through Celtic’s academy and into the first team at the tender age of 18.

Back in 2016, UEFA.com covered Tierney in one of their ‘weekly wonderkid’ pieces, in which they described him as an “all-action, swashbuckling, left-footed wing back” who is a “tenacious tackler when required and never wasted an opportunity to join in with the attack”.

And Celtic captain Scott Brown confirmed this sentiment claiming (via UEFA.com), "I love the wee man, he's as hard as nails. He'd tackle his granny and he'd go into any situation and thrive just because of his attitude. He's a born winner, a born leader and he's a great young lad to come through at Celtic."

Given Arsenal’s questionable defensive record in the Premier League and Kolasinac’s average overall output (which has been rated 6.71 by WhoScored), surely Tierney is the kind of player the club need to shake things up and improve with his overall rating standing at 6.97, (as per WhoScored) without even taking his Scottish Premiership and domestic cup stats into consideration. And, the crazy thing is he's only 22-years-old.

Arsenal climb up the table

Obviously, this one is subject to how well Tierney moulds into the team. Should everything run smoothly, however, and Arsenal’s defence improves, then the Gunners will possibly climb up the table into the Champions League spots.

Why? The Gunners (73) have the third best attacking record in the league behind Liverpool (89) and Manchester City (95). They’ve shown that with the likes of golden boot winner Pierre-Emerick Aubameyang and partner Alexandre Lacazette in attack, they have the necessary firepower to launch themselves towards the top of the table.

But they’re desperately top heavy, and that’s what has let them down this term. Should the Tierney deal pay off, then they're taking one giant leap towards Premier League nirvana.

Arsenal fans, do you agree with our predictions? Let us know in the comments below...