The impact Jurgen Klopp has made at Liverpool since replacing Brendan Rodgers in October 2015 has been nothing short of extraordinary.

Big things were expected of the former Borussia Dortmund coach when he was announced as Rodgers’ successor four years ago, but even the most optimistic Red couldn’t have imagined what would happen over the next few seasons.

Klopp has transformed the team and turned them into European champions. He’s yet to end the club’s long wait for a Premier League title but you sense it won’t be long before that happens.

The charismatic German coach has slowly got rid of the deadwood over the past four seasons and assembled a supremely talented group of players who have all bought into their manager’s philosophy.

But which players are the best signings Klopp has made at Anfield - and which are the worst? We've left out certain players who have made little to no impact, such as Adam Lewis, Daniel Atherton and Liam Millar. Bobby Duncan is included after the headlines made over the past couple of weeks.

21. Dominic Solanke (£6m - 2017)

One goal in 27 appearances is a woeful return from a striker who promised so much during his teenage years.

It looked like Liverpool had pulled off a major coup by securing his services, especially for £6 million, but the young Englishman simply wasn’t at the level required.

20. Bobby Duncan (Free - 2018)

The cousin of Liverpool legend Steven Gerrard, it’s a huge shame what’s happened over recent weeks.

Things quickly turned sour - not helped by his outspoken agent - and the England youth international now finds himself at Fiorentina.

19. Alex Manninger (Free - 2016)

Does he even count?

The retired Austrian goalkeeper didn’t make a competitive appearance for the Reds but we’re sure he did a decent job on the training pitch.

18. Loris Karius (£4m - 2016)

It’s important to remember that Loris Karius made 49 appearances for Liverpool. But the previous 48 appearances were overshadowed by his calamitous performance on the biggest night of his career.

The two goals that he gifted Real Madrid in the 2018 Champions League final will, sadly for him, never be forgotten.

17. Marko Grujic (£5m - 2016)

Marko Grujic is clearly a talent but it’s beginning to feel like he probably won’t make the grade at Liverpool.

The Serbia international, who turns 24 this season, has spent the past few seasons out on loan and has impressed with Hertha BSC.

But will will ever see him holding down a regular place in Liverpool’s midfield?

16. Ki-Jana Hoever (Free - 2018)

Described as “confident” and a “joy to watch”, Dutch defender Ki-Jana Hoever has a big future ahead of him.

He became Liverpool’s youngest player to feature in the FA Cup last season but was left out of the club’s Champions League squad earlier this season.

Despite that, there’s no doubt that Hoever’s long-term future is with the Reds.

15. Sepp van den Berg (£1.8m - 2018)

Klopp always has one eye on the future, hence the acquisition of several young players over the past 12-18 months including Sepp van den Berg.

The Netherlands Under-19 international was named in Liverpool’s Champions League squad this week, suggesting that Klopp may rate the teenager as an even bigger prospect that Hoever.

14. Harvey Elliott (£4m - 2019)

Harvey Elliott is one for the future but Liverpool did well to secure the 16-year-old’s signature in the summer.

The midfielder was on the radar of Europe’s top clubs - including Real Madrid, Paris Saint-Germain and Manchester City - but the Premier League’s youngest ever player opted to join the Reds.

It might not be much longer before we see him competing for a spot in the first team.

13. Adrian (Free - 2019)

Brought in to Liverpool to replace Simon Mignolet, Adrian has found himself playing more than expected during the opening weeks of his spell at Anfield after Alisson suffered an injury.

The Spanish goalkeeper has only made five appearances for Liverpool but has already won the first trophy of his career.

Adrian was in goal for the UEFA Super Cup against Chelsea and won the trophy for Liverpool by saving Tammy Abraham’s penalty.

12. Ragnar Klavan (£4m - 2016)

Ragnar Klavan’s spell at Anfield was fairly brief but he left in the summer of 2018 with the best wishes of Liverpool fans because of the way he conducted himself.

Brought in as a squad player following the departures of Kolo Toure and Martin Skrtel, Klavan made 53 appearances for the Reds, scoring two goals.

He went viral on a couple of occasions for pulling off some utterly pointless ‘skills’ but that’s all part of why fans will always remember the Estonia international fondly.

11. Xherdan Shaqiri (£13m - 2018)

Lots of football fans laughed when Liverpool signed Xherdan Shaqiri from relegated Stoke City in July 2018.

But Klopp knew the Swiss midfielder possessed real quality, even if others couldn’t see it.

Shaqiri made a real impact during his first season at Anfield, repaying back that transfer fee by scoring the final two goals in a 3-1 win over fierce rivals Manchester United last December.

10. Alex Oxlade-Chamberlain (£35m - 2017)

It’s such a shame that Alex Oxlade-Chamberlain missed almost all of last season through injury because he was playing so well prior to the serious knee injury that he sustained against AS Roma in April 2018.

The England international is back now, though, and could be the missing piece that Liverpool need to finish top of the Premier League table above Manchester City this season.

9. Naby Keita (£52m - 2018)

Although we’re yet to see the best of Naby Keita in a Liverpool shirt, we’ve seen enough glimpses to know that he’s a quality footballer.

Klopp is a huge fan of the Guinea international and it shouldn’t be much longer before he cements his status as one of the Premier League’s best midfielders.

8. Joel Matip (Free - 2016)

Joel Matip has become an increasingly important player for Liverpool.

The Cameroon international has flourished since Virgil van Dijk arrived, perhaps needing another commanding centre-back alongside him to truly shine.

7. Fabinho (£39m - 2018)

Klopp signed Fabinho, who has impressed with AS Monaco, to replace Emre Can - and what a job the Brazilian midfielder has done so far.

The 25-year-old has become a key member of the squad, making 41 appearances in his debut campaign at Anfield.

6. Georginio Wijnaldum (£25m - 2016)

Without Georginio Wijnaldum, Liverpool wouldn’t have won the Champions League last season - and for that reason alone, he deserves to be near the top of the list.

The Dutch midfielder, who arrived at Anfield after scoring 11 goals in 40 games for Newcastle United, wrote his name into Liverpool folklore with those two quick-fire goals against Barcelona.

He’s been a tremendous team player over the past four seasons and is clearly a very popular member of the dressing room.

5. Andrew Robertson (£8m - 2017)

One of the best deals in Liverpool’s recent history, securing the services of Andrew Robertson for £8 million looks more remarkable with each passing week.

Is there a better left-back in the world right now?

4. Alisson Becker (£56m - 2018)

After Karius’s disastrous performance in the 2018 Champions League final, it became abundantly clear that Liverpool needed a top goalkeeper in order to win silverware.

Klopp went out and lured Alisson Becker to Anfield and it’s no coincidence that Liverpool win the Champions League in the Brazilian’s first season at the club.

There’s been the odd mistake but, on the whole, the signing of Alisson has been an absolute masterstroke.

3. Sadio Mane (£30m - 2016)

Sadio Mane looked good at Southampton, but nobody knew he was *this* good.

The Senegalese forward continues to improve and is now, without question, one of the world’s best attacking wingers.

2. Mohamed Salah (£34m - 2017)

Thirty-four million pounds now looks an absolute bargain for Mohamed Salah, who has exceeded all expectations since completing his move from AS Roma two years ago.

The Egyptian forward, who struggled at Chelsea prior to his move to Roma, has scored 74 goals in 110 games for the Merseyside outfit.

Salah has established his reputation as one of the world’s best forwards, winning back-to-back Premier League Golden Boot awards over the past two seasons, and would easily fetch around £150 million if Liverpool decided to cash in.

1. Virgil van Dijk (£75m - 2018)

Prior to Van Dijk’s arrival, Liverpool were a mess defensively.

Klopp worked for months to get his man and then finally, in January 2018, Southampton agreed to sell the Dutchman after receiving an offer worth £75 million.

That transfer fee raised plenty of eyebrows at the time - but the 28-year-old has been worth his weight in gold to the Reds.

He was the missing piece in the jigsaw and one of the main reason why Liverpool are now the reigning European champions.