Arsenal had two players provide unexpected breakthrough campaigns this season. One of them, Francis Coquelin, has been well documented, but the other was perhaps even more of a surprise: Héctor Bellerín. The Spanish full-back started the season as third choice right back, behind Mathieu Debuchy and Calum Chambers, with only 9 games of professional experience: 8 for Watford in 2013-14 and 30 minutes in midfield in the Capital One Cup in 2013-14. He made his debut away at Borussia Dortmund, and struggled greatly, as the rest of the Arsenal team did. But, Bellerín made further appearances against Southampton in the Capital One Cup and Hull City in the League and started to play better, with his pace a valuable asset, allowing him to be the attacking full back.
And following Debuchy's second injury, and Calum Chambers' poor showings at right back, Bellerín became the first choice, and was excellent in Arsenal's win at the Etihad, keeping tight to Per Mertesacker, and covering space well. In Bellerín's next game, at home against Aston Villa, he added the 5th with a sweetly struck side-footed 20-yard goal, capping an excellent game. Bellerín was helped by the presence of Nacho Monreal in the side: Monreal provided balance and an example of intelligent movement. Bellerín, a winger when coming through La Masia, has excellent ball skills, with good passing, dribbling, crossing and good off-the-ball movement, which was perhaps best seen when Aaron Ramsey was on the right, with whom Bellerín struck up a good partnership. This was particularly notable in Arsenal's 4-1 thrashing of Liverpool: Bellerín scored the first, coming into the penalty box and scoring with his left, and receiving a pass from Ramsey. Bellerín was also excellent against Aston Villa in the FA Cup final.
Bellerín's story is not just one of a youngster making a surprising breakthrough. When Debuchy got injured a second time, Arsenal could've had the injury derail their season: Calum Chambers had struggled at the highest level, and the other alternative was an out-of-position Mathieu Flamini. Bellerín, though, prevented that: he was consistently very good once he arrived in the first team. His partnership with Per Mertesacker is far better than that of Mathieu Debuchy, with the Spaniard's positioning better than his more experienced counterpart and his pace better to make up for his attacking forays. He brought balance to an Arsenal back four that was lacking balance with Debuchy and Chambers at right back, and improved as the season went on. While there are some aerial weaknesses, he got stronger as the season continued, and even battled well with Marouane Fellaini when Arsenal went to Old Trafford in March, and then again in May.