When a player signs for a football team, there's usually lots of complications that come with it. There's the price tag, the pressure, the change of playing style and the competition for a first team place - all of which can make it hard for players to make an impact at a new club.
But some players just don't get the chance. It's almost like if they don't score a hat-trick in their first game, they're bottom of the pecking order for the rest of the season.
At no club is that more true than at Chelsea. And here's five players who, despite their current reputations, were no more than a squad player when they were at Stamford Bridge.
Just look at them now.
5. Juan Cuadrado
After flourishing at Fiorentina, pacy winger Juan Cuadrado signed for Chelsea in February 2015 for around £24m.
The Colombian winger was a widely sought-after player and at the time was considered an extreme talent. The Guardian named him at number 56 in their top 100 players in the world list for 2014.
After joining the Blues, he started just four times in the proceeding four months of league football, and joined Juventus on loan in summer 2015. He spent two seasons on loan to the Italian champions before they officially acquired him for a fee less than Chelsea paid for him in May 2017 - after helping his side reach the Champions League final against Real Madrid.
4. Mohamed Salah
One of Egypt's finest ever talents, Mohamed Salah signed for the Blues in January 2014 after impressing for Basel in the Champions League. The Swiss outfit beat Chelsea in both fixtures of the 2013/14 group stage, and Salah, who had won the 'CAF African Promising Player of the Year' award in 2012, shone over the two legs.
But Salah had a sporadic appearance schedule. Despite making ten league appearances in the second half of 2013/14 for Chelsea, he was kicked under the rug in 2014/15 and was played just three times before being loaned to Fiorentina in the second half of the season.
But it was at Roma, whom he joined on a permanent deal that summer, where he regained his best form. He was named Roma Player of the Season at the end of 2015/16 with a fantastic goal contribution, and 15 league goals in 31 appearances in the next campaign helped his side to within four points of champions Juventus.
Now at Liverpool, Chelsea will be kicking theirselves for ever doubting him, as he continues to fire them in from the wing for the Reds. Oh yeah - he's just qualified for the FIFA World Cup next year with his national side - and his 32 goals in 56 caps for Egypt is nothing short of phenomenal.
3. Radamel Falcao
It's fair to say that Falcao's career in England was nothing short of a flop, but both Manchester United and the Blues failed to utilise his ability when he joined on loan from Monaco.
Falcao was one of the world's best strikers when he made the move to the UK, but when he failed to make his mark, some thought his career was over. Despite a lethal record of 70 in 91 for Atletico Madrid in all competitions, as well as a rifle shot and fantastic attacking prowess, Falcao was second-in-command to Diego Costa in his one season at Chelsea. He played only ten Premier League games, scoring once. Another Fernando Torres, maybe?
Nope. He scored 30 in all competitions last season and has hit 15 in 16 league games thus far in 2017/18.
What a miss!
2. Romelu Lukaku
This one's another brain bender. Romelu Lukaku, now firing them in for fun at Manchester United at weekends, was on Chelsea's books between August 2011 and July 2014.
The Belgian powerhouse, who drew regular comparisons to Didier Drogba and was hailed as his long-term replacement when he signed from Anderlecht, suffered a torrid spell at Chelsea, despite being a Blue for three seasons.
Having scored 48 goals in 91 games for Anderlecht since his first call up to the team in 2009 aged 16, Chelsea snapped him up for a reported £17m in August 2012. With his already proven record in the Belgian first division, Lukaku expected to be a starter for Chelsea, but had a distinct lack of involvement in his first season.
Next season he was sent on loan to West Brom, and finally got the chance to prove himself in the big league. He scored 17 league goals in 35 games as the Baggies' talisman, and returned to Chelsea looking as promising as ever. But after playing in two league games, he was sent on loan to Everton on the last day of the summer transfer window.
He impressed for the Toffees as well and Everton wasted no time in making his deal permanent in summer 2014. Continuing to blossom as a player, he scored 25 league goals in 2016/17. For Chelsea, he started one game in his entire spell, made eleven substitute appearances, and scored no goals.
1. Kevin De Bruyne
Manchester City's now world-beater Kevin De Bruyne was already tipped for stardom when he joined Chelsea in 2012.
Lukaku's international counterpart had played 97 league games for Gent by the age of 21 when the Blues signed him on January deadline day in 2012 for £7m. That figure seems like a bargain today for such a player, who made his international debut aged just 19.
The player was purchased by the club as an "investment for the future" which then-manager Andre Villas-Boas admitted he had no say in - but De Bruyne was loaned straight back out to Genk for the remainder of 2011/12.
In 2012/13, he was loaned to Werder Bremen, and scored 10 goals in 34 games from midfield, but still Chelsea didn't want to reap the rewards. In 2013/14, his only proper season at the club, he only started a shocking THREE league games - yes, three, and was subsequently sold to Wolfsburg in January 2014 for a profit, having played just 9 games for Chelsea in all competitions.
What the hell were they thinking?