Will Jose Mourinho be a success in his second spell at Chelsea? Only time travellers have the answer to that question. So while we wait to see how the Special One will fare in his return to Stamford Bridge, we delve into the history books to see how other managers who "came home" got on. Some are bizarre, all are interesting…
Graham Taylor - Watford and Aston Villa
1977-1987: Taylor was so keen to be in this feature that he actually returned to two separate clubs. In 1977, he turned down top flight West Brom in favour of an offer from Fourth Division Watford's new owner Elton John. He took the Hornets to the First Division in just five years and kept them there before leaving for a new challenge at…
1987-1990: …Aston Villa, whom he guided to second place before England came calling.
1996-2001: John, himself returning as owner of the Vicarage Road club, re-hired Taylor and once again he led the club back to the top flight. Taylor retired from football after five years at the helm, publicly stating he'd lost his powers of motivation. He came out of retirement a few months later to take over at…
2002-2003: …Aston Villa, where Taylor spent one season before deciding to give it all up for good.
In-between: Just the small matter of England. And turnips. And San Marino. We don't want to talk about it.
Kenny Dalglish - Liverpool
1985-1991: After 355 appearances for the club, the man Liverpool fans call King Kenny first stepped into the Anfield dugout in 1985 and led the Reds to three league titles and two FA Cups.
2011-2012: When Roy Hodgson was shunted out of Liverpool, Dalglish, then working as a club ambassador and with the youth set-up, stepped up to take charge of the first team. He led the side to their first trophy in six years in the League Cup, but the club's worst league finish since 1994 meant Dalglish's three-year contract was ripped up after just 18 months.
In-between: Mixed results. Dalglish took second division Blackburn Rovers back to the top flight for the first time since the 1960s, before going on to win the Premier League, before an ill-fated year at Newcastle was followed by an almost comic stint at Celtic, in which he appointed former Liverpool team-mate John Barnes as head coach.
Leroy Rosenior - Torquay United
2002-2006: Rosenior was one of Torquay's more successful managers, guiding the Devon side to automatic promotion from League 2 in 2004. Despite holding Premier League Birmingham City to a 0-0 draw in the FA Cup, he failed to keep the Gulls in League 1, experiencing relegation on the final day of the season. He left the club languishing near the foot of the table midway through the following season.
2007: In one of the more bizarre stories you'll ever read, Rosenior was brought back into the club to replace Keith Curle - only for a takeover by a local consortium to be announced the very same day. They duly did away with his services in favour of Paul Buckle, giving Rosenior the record of the shortest managerial reign in English football history.
In-between: Rosenior succeeded Martin Allen at Brentford - twenty years after replacing the very same man in the League Cup final for Queens Park Rangers. He lasted just five months after the club went on a run of 16 games without victory. After the brief Torquay return, he turned to punditry.
Steve Bruce - Wigan Athletic
2001: Bruce joined Wigan with just eight games of the 2000/01 season remaining and guided the Latics into the Division 2 (now League 1) play-offs, where they lost to Reading in the semi-finals.
2007-2009: With Paul Jewell unexpectedly resigning having taken Wigan to the top flight for the first time in their history and subsequently kept them there for two seasons in a row, Wigan chairman Dave Whelan reappointed Bruce, who this time stayed for precisely 34 months longer.
In-between: Having left Wigan after eight games, Bruce lasted barely three months at Crystal Palace before he decided Birmingham City was a more glamorous job. He got the Blues back into the Premier League at the first time of asking - a feat he has since repeated at Hull City.
Eddie Howe - Bournemouth
2008-2011: Howe had two spells as a player and manager at Bournemouth and, when a knee injury forced retirement at 29, he took up a position on the coaching staff at Dean Court. Howe was handed the main job in December 2008 with the club 17 points from safety in League 1. He kept them up and 12 months later they were promoted.
2012-present: Howe returned to the south coast in October 2012 and repeated the feat - guiding the club from the League 1 relegation zone to promotion to the Championship.
In-between: After his remarkable achievement in his first stint at the Cherries, the likes of Crystal Palace and Peterborough were vying for his signature. But Howe chose Burnley, who had recently been relegated from the Premier League. He steered the Clarets to eighth place before returning to Bournemouth for "personal reasons".
Kevin Keegan - Newcastle United
1992-1997 Newcastle was both the club at which Keegan ended his playing career and began life as a manager eight years later. His mission was keeping them in the Second Division as, after years of neglect, the Magpies had plummeted down the table. Keegan led them into the Premier League, inspiring a brand of football where the foot was never taken from the accelerator, defence rarely factored in. The title was blown at the end of the 1995-96 season, but the fans still loved him and were devastated when he walked away in January 1997.
2008: A decade later, and the club searching a new manager, owner Mike Ashley caved to fan pressure and gave Keegan a second stint at St James' Park. They started the season well, but Keegan fell out with the board and resigned once again.
In-between: Keegan took over at then second division Fulham, where he gained promotion. He resigned to take over the England job where he guided them to Euro 2000 - but failed to get out of the group stages. He quit after a 1-0 defeat to Germany in the last ever game played at the old Wembley stadium with the lowest win percentage of any England manager in history - at 38%. After England he spent four years at Manchester City, including getting them back into the Premier League. But in 2005 - you guessed it - he resigned.
Howard Kendall - Everton
1981-1987: One of Everton's greatest players, Kendall was just 35 when he took over a club in the shadow of its Merseyside neighbours. But the 1984 FA Cup was followed by two league titles in three seasons. However, the Heysel riot of 1985 had stopped Everton playing in the European Cup, and a frustrated Kendall walked.
1990-1993: Kendall returned three years later with the club battling relegation. He led them to ninth place, but the magic was gone. Everton had never recovered from the European exile or his departure.
1997-1998: Kendall returned to Everton in 1997, with the club seemingly as out of ideas as he was. Everton left at the end of the season, having avoided relegation on the final day.
In-between: Two years in Spain with Athletic Bilbao were followed by a return England with Manchester City - "an affair from my marriage to Everton." Between his second and third Goodison Park spells, he had a year in Greece with Xanthi, a season with Notts County and two years at Sheffield United, with minimal success.
Tony Pulis - Stoke City
2002-2005: Pulis took over at the Britannia with the club destined for relegation, but they survived on the final day - an achievement Pulis still rates as one of his finest. The following season the Potters finished in 11th, but Pulis quit after falling out with the club's Icelandic owners over funds - though they insist he was sacked for "failing to exploit the European transfer market".
2007-2013: When Peter Coates took over at Stoke, he re-appointed Pulis and the Welshman led the club to the Premier League - where they have since established themselves, including an FA Cup final appearance. Pulis left Stoke last month after narrowly avoiding relegation and was replaced by compatriot Mark Hughes.
In-between: Pulis spent a season at Plymouth Argyle between his spells at Stoke, guiding the Devon club to 14th in the Championship.
Steve Coppell - Crystal Palace
1984-1993: Remarkably, four of Coppell's first five jobs as a manager were at Crystal Palace. He took over at Selhurst Park aged just 28 when injury ended his playing career. Coppell guided Palace to the top flight and to third place - their highest ever league finish - as well as an FA Cup final and the club's first major trophy - the short-lived Full Members Cup. Coppell resigned when the club were relegated in 1993.
1995-1996: After two years of not doing very much, Coppell returned to Palace as director of football, with Ray Lewington and Peter Nicholas as his assistants, but midway through the season the club decided the system wasn't working and appointed Dave Bassett as manager.
1997-1998: After a (very) brief stint at Manchester City, Coppell returned to Palace as chief scout. But two weeks later Bassett resigned and Coppell once again found himself in the hot seat. He steered them to promotion and a boardroom takeover led to Coppell moving back to the director of football role, with Terry Venables coming in as head coach.
1999-2000: Venables didn't last long and that man Coppell found himself in charge of the team for the fourth time. Crippled by debt, Coppell steered the club to safety before mobile phone magnate Simon Jordan took over the club and sent Coppell packing.
In-between: Between his second and third Selhurst stints, Coppell was at Manchester City for just 33 days before quitting - citing too much pressure. Since leaving south London, Coppell has managed Brentford, Brighton, Reading and Bristol City. He is currently director of football at League 1 Crawley Town.
Harry Redknapp - Portsmouth
2002-2004: Having left West Ham a year earlier, Redknapp guided Portsmouth to promotion to the Premier League - replacing the Hammers in the top flight in the process. Redknapp kept Pompey up the following season, but resigned after a disagreement with owner Milan Mandaric over the hiring of director of football Velimir Zajec.
2005-2008: Redknapp re-joined Portsmouth a year later with the club threatened by relegation. They survived and the following season finished ninth, their highest league placing for more than half a century. The reign culminated in FA Cup glory and Redknapp was granted the freedom of the city before hot-footing it to Tottenham Hotspur.
In-between: Controversially, Redknapp spent a year at Portsmouth's bitter south coast rivals Southampton - a move which infuriated the Fratton Park faithful, who bore t-shirts describing Redknapp as 'Judas'. The season ended in the Saints tumbling out of the top flight for the first time in 27 years.
Alex Perry is assistant editor at ESPN and can be found tweeting here