Chelsea have been quiet this summer transfer window, and their 1-0 defeat to Arsenal in the FA Community Shield on Sunday along with their preseason in general has highlighted why that might hurt their title defense.

The champions had a lacklustre first half marked by a 24th minute goal by Alex Oxlade-Chamberlain for the Gunners. In the second half, they managed to pull themselves together and dominate in Arsenal’s half, putting pressure on Arsenal’s back line, however, basically doing everything but score.

After the final whistle, the Blues had to face the facts: the winning Arsenal side had been quicker, more cohesive, and had been able to finish when it counted.

José trusted about 10 players last season. Yet, he’s happy with the squad this season despite no investment thus far? — Tweeds (@JTweedsPOA) August 2, 2015

Since the end of the 2014-15 season, the Blues haven’t gotten quicker or more cohesive. Their only big signings were Radamel Falcao (on loan) and Asmir Begovic to replace the outgoing Didier Drogba and Petr Cech, respectively.

They’ve also sold Filipe Luis to Atletico Madrid this summer, meaning the Blues have no back-up for Cesar Azpilicueta, who did not have his best game against Arsenal on Sunday going up against Oxlade-Chamberlain.

Chelsea’s Community Shield loss to Arsenal also resembles what 2013-14 Premier League champions Manchester City experienced in last summer’s Community Shield. Manuel Pellegrini had not made significant additions to his squad, and City lost the Community Shield to Arsenal before a poor Premier League title defense saw the league title go to Chelsea.

Attacking additions are needed

While the Community Shield cannot predict who will win the Premier League, it can reveal which teams are stronger after the summer and which teams are weaker.

Chelsea seem weaker simply because they have not strengthened, following the same pattern that City adhered to before them by attempting to retain the title with the same squad they won it. Of course, City bought Fernando and Eliaquim Mangala but they didn’t really strengthen the first XI.

You get people in early so they have a preseason with the squad. Not panic buying when we’ve already started the season. — Tweeds (@JTweedsPOA) August 3, 2015

If Jose Mourinho hopes to lead Chelsea to a second title victory in a row, then it is imperative that he strengthen two key areas in his team.

Firstly, he needs to find a suitable left-back, such as Blues target Abdul Rahman Baba, and seal the deal.

Azpilicueta has been consistent on the left for Chelsea, living up to Mourinho’s claim that he is “the greatest left-back in the Premier League.” However, he will have the occasional game where he cannot make an impact, such as Sunday’s game, and Mourinho needs to have a reliable backup for him in those cases.

A deal with FC Augsburg for Baba Rahman is considered to be all but complete, and the sooner the better.

Secondly, and more direly, Mourinho needs to strengthen Chelsea’s attack. He may have good attacking options on paper, but yesterday’s defeat has revealed that they are not enough.

Diego Costa proved he is a prolific striker last season with 20 goals for the Blues. However, he struggled with injuries throughout the 2014-15 campaign and is likely to do so this season too, missing Sunday’s clash with Arsenal due to “discomfort in his hamstring.”

Even Mourinho has admitted that Costa has problems staying healthy, and it is certain that the Portuguese manager can expect to have to rely on other strikers at times in the 2015-16 campaign in order to avoid serious injury to his star striker.

That leaves Loic Remy and Falcao as strike options, both of whom played in yesterday’s defeat. Remy started up top, but the Frenchman had a poor game as he was offside too often and could not link up well with Eden Hazard or impress in Chelsea’s attacking third.

He was replaced at halftime by Falcao, who displayed poor form while on loan at Manchester United last season and is known to be injury-prone.

The Colombian striker has not had much time to settle into Chelsea’s squad yet, and Mourinho may well bring out the best in him. However, the fact remains that Falcao was not able to influence the game as much as he would have liked against Arsenal.

And it’s important that the Blues start off on the right foot Saturday in their first Premier League match of the season, in which it looks likely that he will start.

Adding another strike option, such as Antoine Griezmann, could prove the difference between retaining the title or following the same pattern Manchester City did last season. Griezmann scored the third most goals (22) in La Liga last season and was sensational in his first season with Atletico Madrid.

However, despite interest from Chelsea and Bayern Munich, the Frenchman claims that he has heard nothing of interest from other clubs, insisting, “Nothing from anyone reached me and I repeat that I only want to help the team.”

The 24-year-old seems determined to stay at the Vicente Calderon, but if Chelsea can pry him away for a price believed to be around £28.5 million, they will have gained a badly needed, reliable and versatile forward.

Of course, Mourinho could also strengthen Chelsea’s attack by adding another attacking midfielder to take the burden off of Hazard a bit.

The Belgian is regarded by many as the third greatest player in the world, but even he occasionally misses a golden opportunity, an example being a beautiful through ball he received from Cesc Fabregas that he kicked well over target against Arsenal and is prone to underperforming in the slightly bigger games.

Mourinho was interested in Barcelona left-winger Pedro in July, but it now seems likely that the Blues have missed their opportunity as Manchester United are closing in on his signature.

Nevertheless, having another world-class winger such as Pedro would have taken the pressure off of Hazard and allowed him to take a break every now and then and even play centrally more often.

It is even more surprising that they aren’t pursuing anyone given Mohamed Salah’s departure to Roma and Juan Cuadrado’s lacklustre displays for the Blues so far.

Mourinho still believes title can be retained with same squad

Chelsea have been stagnant this summer; they’re undoubtedly still a strong side, but they haven’t gotten better. Meanwhile, their rivals have strengthened and would love nothing more than to take down the former champions.

“We are not worried about the others, what they buy, what they have, what they spend – I don’t care,” Mourinho claimed in regard to the spending of clubs such as Manchester City, Manchester United, Arsenal, and Liverpool. “I think it is normal (for Chelsea’s title to provoke such a strong reaction from the other clubs). I am happy with the challenge of fighting against these powers.”

Although Mourinho may not seem concerned, what happened on Sunday indicates that he should be.

Claims from Mourinho that the players on his squad can “be better individually than last year” and from Andy Cole that Chelsea “don’t need to [spend] because they have a very good squad there already” seem misguided after watching Chelsea’s attack fail to deliver against FA Cup winners and title rivals Arsenal, and then fail yet again against Fiorentina three days later.

Preseason friendlies may not mean much, but nevertheless, the Premier League champions should not have had so much trouble winning them.

I know "it's only preseason" but we play this weekend, not 6 weeks from now. Can't remember us having more than 5 shots total in ~ 5 games. — Tweeds (@JTweedsPOA) August 5, 2015

It's been so clear since Jan that we need strengthening. Not sure what the club is planning on achieving next season. Anyone??? — Mourinholic (@Mourinholic) August 6, 2015

If Chelsea hope to not only retain their title but also avoid another early exit from the Champions League, it would be best if Mourinho loosens his purse strings and really pursues a forward such as Griezmann or Pedro.

Otherwise, it looks like the trend of a team failing to retain the Premier League title since Manchester United did it in 2009 is set to continue.