Appearances: 24+4 (starts + substitute appearances)
Nathan Ake was one of the standout performers on loan this season, forcing his way into the starting eleven of newly-promoted Premier League side Watford and establishing himself as the first-choice left-back, where he played in all but one of his appearances. He was forced to shift to central defence once, against Leicester City, and did a stellar job of keeping Jamie Vardy quiet. Although his preferred position may be in central midfield, Ake acclimatised to his new left back role very well. He's come a long way since his first few tries at outside back for the Chelsea youth teams, and was a key component of Watford's cohesive defensive unit.
Playing as a left-back in Quique Sanchez Flores's 4-4-1-1 formation meant that Ake had to press high up the pitch, and when in possession, immediately look to find a striker (either Odion Ighalo or Troy Deeney). This direct approach, combined with his tendency to misplace the odd short, easy pass, meant that Ake's passing statistics weren't as high as they should've been (only 72% successful). Despite the numbers, the 20-year-old generally looked comfortable and composed when playing the ball out of defence.
Although fairly proficient when it comes to aerial duels (1.5 successful per game; only Cathcart, Britos and Deeney won more), Ake lost several crucial battles in the air, such as against Connor Wickham in the FA Cup semi-final and against Alexis Sanchez (!), both of which led to goals. I believe that this aspect of his game will improve with additional, consistent (and high-pressure) game-time.
The strongest aspects of Ake's defending are his tenacious tackling and excellent anticipation and reading of the game. He averaged 3.3 successful tackles (highest among Premier League defenders with at least 15 appearances) and 3.2 interceptions per game, highest on the team. Although, due to his swashbuckling tackling technique, he's prone to a committing a few fouls.
Ake had a number of players playing in front of him on the left wing, such as Jurado, Nordin Amrabat, Almen Abdi and even Etienne Capoue. When paired with the former two, he naturally tended to make more frequent ventures forward and linked up well, though his ability to take-on players and deliver a good cross needs work.
Ake's form tapered off towards the end of the season as he seemed to experience a bit of a burn-out, but his time at Watford ended on a high note when he collected their Young Player of the Year award.
Witness his defensive prowess yourself in this compilation of some of his defensive actions when playing as a centre-back against Leicester City.
Verdict: It was a great season for Ake, who arguably has exceeded even his own targets at the beginning of his loan spell. He played regular football at the highest level and looked the part for sure. He's earned the right to try and impress Antonio Conte in pre-season and hopefully play for the first team next year.
Bonus Points: He also has fabulous hair and looks like Ruud Gullit, in case you hadn't noticed.