7 players sold at the right time including Man Utd and Liverpool stars

Knowing when to let go of a valued player can be just as vital as knowing when to hold on, and Manchester United demonstrated this 10 years ago when selling Park Ji-sung to Queens Park Rangers.

Park had played more than 200 gams for United across seven seasons. A short while after his exit, though, it had become clear his time at the top of the English game was over.

The South Korea international managed 20 league appearances for Mark Hughes' side, but he and the team struggled during a difficult relegation campaign. United only brought in a seven-figure fee for the midfielder, but he's an example of a club knowing when to offload a player and refusing to let emotions get in the way. Here, Mirror Football picks out a few more examples.

Park Ji-sung

"I didn't cry about it yesterday, and I'm not crying about it today, that means I'm leaving with no regrets," Park said in 2014 upon hanging up his boots. After suffering relegation with QPR he returned to PSV Eindhoven on loan, but called it a day after one last season in the Eredivisie.

"I enjoyed playing football. I have achieved more than I have thought I would. I'm truly grateful for all the support I have received and I will live the rest of my life thinking how I can pay it back."

Injuries had got in the way during that one top-flight season with QPR, limiting his involvement. While United didn't sell Park at the peak of his financial value, they did so at a time when he had perhaps given them all he could.

Bastian Schweinsteiger

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United found themselves on the opposite end of a similar deal just a few years later. Schweinsteiger might have only set them back £6.5m, but perhaps the Red Devils should have questioned why Bayern Munich were so willing to part ways with the long-serving player.

Schweinsteiger ended his spell in Bavaria with 500 senior appearances, and there's an argument that he was feeling that game time in his legs by the time he arrived at Old Trafford. Injuries restricted him to just 35 games for the club, with just four of those coming after Jose Mourinho's arrival as manager in 2016.

The German veteran did manage to play more football after crossing the pond and joining Chicago Fire. There are few at Bayern who will have felt they let go too early, though.

Philippe Coutinho

At the other end of the financial scale is Coutinho. The Brazilian had been strongly linked with Barcelona long before his January 2018 switch, but his £142m move will go down as one of the worst investments in recent memory.

While Coutinho's first few months at Camp Nou were far from terrible, things soon went south. He was eventually sold to Aston Villa at a huge loss, while his Champions League triumph during a loan spell at Bayern Munich added insult to injury.

Liverpool, meanwhile, didn't miss the former Inter Milan man one bit. Their first full season without Coutinho saw them win the Champions League, with a first Premier League title following one year later.

Freddie Ljungberg

Ljungberg will forever be remembered fondly by Arsenal fans. However, West Ham supporters might not feel the same.

The Swede played his part in two title-winning campaigns for the Gunners, including the Invincibles campaign. The Hammers may have felt they were getting a bargain, but injuries prompted them to offload him just one year into what was meant to be a four-year contract.

"Two players who signed in the summer 2007 transfer window, one of whom has since left the club, have started a combined total of 32 games and will have cost the group £34m over the term of their contracts," finance director Nick Igoe would later say (per The Totally Football Show ), referring to Ljungberg and Kieron Dyer. "No football club can sustain this level of expenditure on underperforming members of its squad."

Theo Walcott

Speaking of Arsenal players sold at the right time, the club got £20m for Walcott. As recently as January 2018.

While Walcott wasn't consistently great in a red shirt, he gave supporters plenty of memorable moments and scored 19 times in his last full season in North London. That was seemingly enough for Everton manager Sam Allardyce to overlook the fact that he'd barely played in the first half of the 2017-18 campaign.

Walcott didn't match that 19-goal tally for Everton. In fact, in the four-and-a-half years since leaving Arsenal, he's barely got halfway towards that total despite playing more than 100 games for Everton and Southampton.

Fernando Torres

Fernando Torres missed the end of the 2009-10 season after going in for surgery, and didn't really look back to his best the following season. However he did, crucially, score both goals in a November victory over Chelsea.

While that might not have been the only factor in Chelsea breaking the bank for Torres in January 2011, it can't have hurt Liverpool's efforts to make big money on the Spaniard. And that £50m swiftly looked like a wonderful bit of business.

One goal in 18 appearances before the end of the season set the tone. While things did pick up for Torres in the following years, the improvement was never enough to justify the fee. It's just a shame for Liverpool that their replacement - Andy Carroll - didn't fare much better.

Eden Hazard

Chelsea might not have got the rub of the green with Torres, but the tables would turn in 2019. Hazard left for Real Madrid after leading the Blues to Europa League glory, and the Hazard of Chelsea has still yet to show himself in Madrid white.

It would have looked like a bad deal for even half of the initial £85m fee. Indeed, some have called him one of the worst signings in Real Madrid's history, if not the entire history of La Liga.

Yet again, injuries have been a factor, with the Belgian playing just 48 times in three league seasons. He's not the only one to struggle after a big-money Madrid move, though, with fellow big-money signing Luka Jovic featuring even less before making a permanent departure for Fiorentina.