1. Club Overview (around 2016/17)

• Club name: 1. FC Union Berlin (commonly "Union Berlin")
• Country: Germany
• Stadium: Stadion An der Alten Försterei (capacity ~22,012 at that time)
• League (2016/17 season): 2. Bundesliga (second tier of German football)
• Head coach (brief spell): Jens Keller — he was appointed as Union Berlin head coach in late October 2016, replacing Norbert Düwel, and led the team through the remainder of the 2016/17 season.

2. 2016/17 Season Summary

• League finish: Union Berlin finished mid-table in the 2. Bundesliga in 2016/17 (they ultimately placed 6th in the 2016/17 table).
• Managerial timeline that season:
  • Norbert Düwel began the season as head coach but was dismissed after a poor start (October 2016).
  • Jens Keller was appointed late October 2016 and remained for the rest of the season, stabilizing results and improving form.
• Playing style & squad notes: Under Keller the team focused on defensive organization and physical work-rate typical of Union's pragmatic approach. Key squad members around that period included goalkeeper Andreas Luthe, captain Christopher Trimmel (right back), defensive and midfield contributors such as Steven Skrzybski, Sebastian Polter (forward; Polter had been a notable striker though his prominence varied with injuries/transfers), and Toni Leistner (defender).
• DFB-Pokal (German Cup): Union participated in the DFB-Pokal but did not make a deep run in the 2016/17 edition.

3. Jens Keller — brief profile (in that context)

• Full name: Jens Keller
• Born: 24 November 1970
• Coaching background before Union: Previously managed FC Schalke 04 (2010–2011), Eintracht Frankfurt (caretaker 2016), and VfB Stuttgart (2017 later). He was known for pragmatic, disciplined setups and experience in the Bundesliga.
• At Union (2016/17): Took over a struggling 2. Bundesliga side, stabilized results and helped the club climb the table to a comfortable mid-table finish that season.

4. Notable context & legacy

• Union Berlin in the mid-2010s was a club with strong fan culture and steady infrastructure improvements (the stadium and fan-driven projects are a hallmark of the club).
• Keller’s tenure was part of a transitional phase; Union would later continue its rise and eventually achieve promotion to the Bundesliga in the 2018–19 season under coach Urs Fischer.

5. Sources & reliability

• The above summarizes widely reported facts about Union Berlin and Jens Keller’s appointment and role in the 2016/17 season based on match records and press reports from that period.