The burdens on Keegan Rosenberry were both mental and tactical coming into 2018. After a stellar rookie season was tarnished by sophomore struggles and eventually a benching, Rosenberry needed to prove that he could rediscover his defensive positioning compass without sacrificing the most unique part of his game: An ability to break lines and combine quickly from a fullback position. The Union, intent on building from the back, set on shaping an identity through possession, needed Rosenberry's attacking skills to allow the team's wingers to push up and threaten the opposition back line.
Only four fullbacks that played 2000 minutes were involved in a greater percentage of their team's passing chains than Rosenberry in 2018. Additionally, the Union defender managed to remain heavily involved in the attack while playing as part of the ninth best defense -- measured by both Goals Against/96 minutes and Expected Goals Against/96 minutes on AmericanSoccerAnalysis.com -- in the league. For Rosenberry, this was a true 'prove it' season, and he did.
To be sure, the Union's right back was far from perfect. There were moments and, rarely, entire halves (against Dallas, for example) in which he looked at sea. But nothing approached last season's issues, and when Ray Gaddis moved to the left, Rosenberry became one of the most critical players in the Union's attack. As Philly sought to build from deep, Rosenberry had to recognize when to move forward to provide a line-breaking option and when to hang back. One of the smaller tactical tweaks that Jim Curtin and his staff often employed was moving between holding the fullbacks deeper to provide options in the first phase of buildup play and pushing them beyond the first line. It's not something many people noticed, but Rosenberry had to live it game to game, reading and responding.
And as the Union advanced up the pitch, Rosenberry's role became something like a quarterback's on a read-option play. He had to play fast and he had to move, but should he push forward up the wing? Through the channel? Could he trust his teammates to possess the ball when he ventured into the final third? That trust between Rosenberry, Ale Bedoya, and Borek Dockal was one of the culture-driven, intangible elements that allowed Philadelphia to overcome the limited impact of David Accam and CJ Sapong early in the season. Overloads on the right produced gaps that the intelligent Bedoya and Dockal filled; Rosenberry needed to be able to abandon his post intentionally so Dockal could sneak out to the wing and whip crosses onto Cory Burke's head or bring Haris Medunjanin into play.
"Keegan had his best season as a professional," Jim Curtin said after the season. "His ability to add to our attack on the right hand side was really good, but most importantly I thought he improved his aggressiveness and 1v1 defending."
In short, Rosenberry's season was one of risk-taking. He certainly had his oopsie-moments, including a few throw-ins through the center that resulted in turnovers and a hand held up in apology. He also had, just as certainly, moments of unique intelligence, such as the chances he created off quick throw-ins (see Ilsinho's stunner against Chicago for evidence).
On a team that leaned heavily to the right side, Rosenberry's skill on the ball may have been irreplaceable in 2018. He's still not perfect, but he was close to perfect for the system the Union ended up using as injuries and form shaped Jim Curtin's strategic approach.
With Borek Dockal's status yet to be resolved, Philly may not emulate their lean to the right next year, so Rosenberry must continue to grow the defensive side of his game. Fullback is a difficult position to fill, and top-tier two-way fullbacks are a rare breed in MLS. Rosenberry isn't there yet, but he used 2018 to show that his sophomore season will not define him as a professional. Now Union fans will hope he can continue on an upward trajectory next year.