SPFL: How Celtic's Summer Signings Have Fared

Unbeaten in the Premiership, knocked out of Europe. That's pretty much Celtic's season so far in a nutshell. 

With the loss of key players such as Victor Wanyama (to Southampton), Kelvin Wilson (to Nottingham Forest) and Gary Hooper (to Norwich), the Hoops had to be smart in the transfer market during the summer.

While they made almost £21 million from player sales, the six new signings who were brought in made up a combined £9.5 million. 

After the club's lacklustre exit from the Champions League, questions have been asked about the quality which was signed to replace Wanyama and Hooper.

Now, almost halfway through the season, we take a look at how these new players have fared since arriving in Glasgow.

Virgil Van Dijk

Marco Luzzani/Getty Images

Age: 22

Position: Centre-Back

Fee: £2.6 million (from FC Groningen)

Apps (starts): 24 (22)

Goals: 2 

From the summer signings, Virgil van Dijk has been the most successful. 

At 6'4", the Dutch colossus was suited to playing in Scotland from the outset. However, it's been his ability on the ball which has endeared him to the Parkhead faithful.

After coming out of the club's admittedly disappointing Champions League campaign as the team's star performer, with Mikael Lustig, he surely stands a legitimate chance of making the Netherlands squad for next year's World Cup if he continues his impressive form.

Steven Mouyokolo

Jan Kruger/Getty Images

Age: 26

Position: Centre-Back

Fee: £0 (free agent)

Apps (starts): 2 (2)

Goals: 0

Former Wolves centre-back Steven Mouyokolo started fairly well, but unfortunately the injury curse which has plagued his career to date struck again after only two competitive appearances when he ruptured his Achilles tendon during training.

He remains out and is not expected back in action until late February.

Considering he signed a one-year deal, the Frenchman will have less than three months to save his Celtic career.

Nir Biton

Johannes Simon/Getty Images

Age: 22

Position: Central Midfielder

Fee: £722,000 (from FC Ashdod)

Apps (starts): 10 (5)

Goals: 0

Two defeats and a sending off characterised the first month or so of Nir Biton's Celtic career.

Since then, he has gradually settled into a run of solid, if uninspiring, displays in the centre of midfield.

It was always going to be hard for him to displace the likes of Scott Brown and Joe Ledley, but now that Charlie Mulgrew has converted to central midfield, he has even more competition.

The silver lining for Biton is the ever-increasing speculation that Ledley will not be at the club beyond this season, though that is something the Welshman denies.

Derk Boerrigter

Mark Runnacles/Getty Images

Age: 27

Position: Left-Winger

Fee: £2.2 million

Apps (starts): 15 (7)

Goals: 1

Derk Boerrigter was the surprise signing of the summer for Celtic.

He was 26 when he arrived—considerably older than the typical Hoops targets of the past few years.

More than that, he was also a player who had just won the Dutch Eredivisie and appeared in almost 50 matches in a season for Ajax.

There have been flashes of real quality from the Dutchman, and his crossing ability threatens to be one of the best the club has seen since Steve Guppy.

However, the disappointing return of just one goal in 15 games, from a man who hit the net 38 times in the past three seasons, serves only to reinforce the frustration at a player who could clearly be a leading light for the Scottish champions.

Teemu Pukki

Richard Heathcote/Getty Images

Age: 23

Position: Striker

Fee: £2.2 million

Apps (starts): 18 (12)

Goals: 3

Celtic's biggest signing of the summer, Teemu Pukki arrived from Schalke with a reputation as a "super sub"—half his eight goals for the Bundesliga side were after he came off the bench.

He started brilliantly, following up a debut goal away to Hearts with a classy display and another goal against St Johnstone at home.

Since then, however, he hasn't had much luck—his only other strike coming against Hibs last weekend.

The technical quality is definitely there with Pukki, but Gary Hooper he is not; the burden of scoring 25 goals a season may not be one suited to him.

Amido Balde

Jan Kruger/Getty Images

Age: 22

Position: Striker

Fee: £1.5 million

Apps (starts): 12 (2)

Goals: 2

Amido Balde was signed to give Celtic a different option up front—a target man.

The problem is Neil Lennon rarely wants to use one, and when he does, he opts for long, cross-field balls to a usually wide left Georgios Samaras.

In Balde's 14 appearances, he's scored just twice. What the raw stats don't say, however, is that he has actually played the equivalent of just under three full games.

Now that Celtic's focus is fully on domestic activities, it may be time for Lennon to give fringe forwards like Balde and youth team product Bahrudin Atajic more opportunities.