Question: What new coach previously assisted a former player for the Go Ahead Eagles?
Context: Sjoerd Overgoor (born 6 September 1988) is a Dutch professional footballer, who currently plays for Go Ahead Eagles in the Dutch Eredivisie.  He formerly played for De Graafschap, Go Ahead Eagles and Szombathelyi Haladás. Martin Haar (born May 2, 1952 in Zwolle, Overijssel) is a retired football defender from the Netherlands, who is the current serving as assistant coach at AZ Alkmaar.  He played for Go Ahead Eagles (1971–1977), HFC Haarlem (1977–1983), AZ '67 (1983–1986), HFC Haarlem (1986–1988), Sparta Rotterdam (1988–1989) and FC Wageningen (1989).  He was a member of the famous Haarlem team, that competed in the UEFA Cup in the 1982-1983 season, for the first time in the club's history.  However this campaign was to be overshadowed by the Luzhniki disaster. Lambertus "Bert" van Marwijk (] , "surname isolated": ] ; born 19 May 1952) is a Dutch football manager who last coached Saudi Arabia national team.  As a footballer, he played for the Go Ahead Eagles, AZ, MVV and Fortuna Sittard amongst other clubs, and represented the Netherlands once. Jasper Heusinkveld (born 24 December 1988) is a Dutch professional footballer who last played as a goalkeeper for De Graafschap in the Dutch Eredivisie.  He previously played in the Eerste Divisie for Go Ahead Eagles. Theodorus "Theo" Antonius Marie Zwarthoed (born 19 November 1982 in Volendam) is a professional Dutch footballer who last plays as a goalkeeper for SBV Excelsior in the Dutch Eerste Divisie.  He previously played for AZ, SBV Excelsior, RKC Waalwijk, De Graafschap and Go Ahead Eagles. The 2009–10 season was the first season under new coach Mario Been.  The former Feyenoord striker was manager of N.E.C., and has been assistant-coach of Bert van Marwijk at Feyenoord in the past.  Feyenoord welcomed five new players: Dani Fernández came over for free from N.E.C., Sekou Cissé signed a four-year deal after his transfer from Roda JC, Kamohelo Mokotjo came over from Supersport FC and loan agreements were made with Borac Čačak for Aleksandar Ignjatović, and with Nantes for Stefan Babović. Sergio Padt (born 6 June 1990) is a Dutch footballer who plays as a goalkeeper for FC Groningen in the Dutch Eredivisie.  Padt previously played on loan from AFC Ajax for HFC Haarlem in the Eerste Divisie, and later for Go Ahead Eagles and in the Belgian Pro League for AA Gent.  He represented the Netherlands U-17 team at the 2007 UEFA European Under-17 Football Championship. Johannes Gerrit "Johan" Derksen (born 31 January 1949) is a Dutch sports journalist and former football player.  He played professional football between 1966 and 1978 for five clubs: Go Ahead Eagles, Cambuur Leeuwarden, BV Veendam, HFC Haarlem, and MVV Maastricht.  During and after his active career, he became well known as a sports journalist, specialising in football.  He was the editor-in-chief of Voetbal International from 2000 until his retirement on 1 August 2013, the country's most prominent football magazine.  He is also a television football pundit on RTL7's Voetbal International. Glynor Plet (born 30 January 1987 in Amsterdam) is a Dutch footballer with Surinamese roots, currently playing for Alanyaspor.  He previously played for FC Den Bosch, Telstar, Heracles Almelo, Genk, FC Twente, Hapoel Be'er Sheva F.C, Go Ahead Eagles and Zulte Waregem. Demy Patrick René de Zeeuw (] ; born 26 May 1983) is a Dutch footballer who last played for NAC Breda and the Netherlands national football team.  He is a defensive midfielder described as a good tackler and a gifted passer of the ball.  He previously played for AGOVV, Go Ahead Eagles, AZ and AFC Ajax.  While at AZ he was a key player in the squad that won the 2008–09 Dutch league, the club's first championship victory in 28 years.  Following this success he transferred to Ajax, with whom he won the 2009–10 Dutch Cup, and the 2010–11 Dutch league title.
Answer: Mario Been