As has been seen with Frank Lampard at Chelsea, the old adage isn't always true that a successful player has a fruitful managerial career.Five great players who failed to make it as managersSome of the best managers in the modern game did not have the best careers as players. Jose Mourinho, Jurgen Klopp and Arsene Wenger are a few names in this regard.On that note, let's have a look at five great players who struggled as managers:#5 Gianfranco Zola(West Ham, Watford, Cagliari, Birmingham City)Gianfranco ZolaChelsea and Parma legend Gianfranco Zola is regarded as one of the best playmakers of his generation.Zola was involved in 232 goals (200 goals, 32 assists) in 665 appearances in his stellar career, but he never managed to replicate the same exploits as a manager.The Italian had a solid debut season as the manager of the Hammers, ensuring a ninth-place finish, but things unravelled in the next season. West Ham narrowly escaped relegation, and Zola was relieved of his duties.He enjoyed another strong start with Watford, but witnessed a dip yet again. One win in 11 games led to Zola's resignation, and he ventured back home to take over the reins at Cagliari Calcio. Zola faced the boot after just three months at the club, though, after winning just two of his ten games in charge.The Italian's next managerial stint was at English Championship team, Birmingham City. The Blues were a strong contender to make the playoffs, but Birmingham found themselves just three points off relegation, and Zola resigned.OFFICIAL: Gianfranco Zola has this evening resigned as Blues manager. Further details later on https://t.co/msWvrYX7SN #BCFC pic.twitter.com/hNJX1DQudf— Birmingham City FC (@BCFC) April 17, 2017#4 Gary Neville(Valencia CF)Gary Neville12-time Premier League and 2-time Champions League winner Gary Neville was one of the best full-backs in the modern game and was a mainstay in Sir Alex Ferguson's all-conquering Manchester United.The Class of '92 graduate won 30 titles in 19 successful seasons at the club, making 602 appearances for England's most successful team. While Neville won some of Europe's biggest titles in his illustrious career on the pitch, there was a lot to be desired in his time off it.It was somewhat of a shock when Neville took over the reins of Valencia mid-season in 2015. Fans and pundits were apprehensive of his appointment, as Neville had no prior managerial experience. The concerns turned out to be true, as the Englishman faced the sack after less than four months at the Mestalla.Gary Neville's record as Valencia manager compared to Solskjaer's last 28 games in charge of Man United 👀 pic.twitter.com/m5p2S4HqGB— ESPN FC (@ESPNFC) November 7, 2019In his brief managerial career, Gary Neville oversaw Valencia to just three wins in 16 league matches, which produced no clean sheet.The lowest moment was a 7-0 thrashing at the hands of Barcelona in the Copa Del Rey semis. After slipping to 14th in the table and getting dragged into a relegation fight, Valencia decided to part ways with the current Sky Sports pundit.