Adrian Clarke looks at summer signings who can have a big impact for their clubs in 2019/20.
Haller was outstanding for Eintracht Frankfurt last season, providing 15 goals and nine assists in 29 Bundesliga appearances. He also hit the net five times in the UEFA Europa League.
He boasts all the qualities of a complete centre-forward.
Haller is strong in the air, quick, skilful, excellent at linking up with midfielders and shows touches of flair.
If the 25-year-old can reproduce his 2018/19 form in the Premier League, he will soon be a hit with West Ham fans.
Manuel Pellegrini's new signing can fill that void. In fact, statistically the 6ft 2in recruit poses a similar threat from headers as Carroll.
That should encourage West Ham's full-backs, wingers and central midfielders to deliver more crosses.
Haller is especially adept at knocking the ball down for team-mates inside the area and flicks it on well both in the air and on the deck.
That ought to give the Hammers midfielders confidence to make supporting forward runs.
Haller should start the season with great self-belief after directly contributing to a goal every 90.9 minutes last season.
He is a natural predator but can also produce moments of magic, having scored a couple of magnificent volleys last season and had the confidence to round the 'keeper in 1v1 situations.
Haller also has the talent to unlock defences with a pass or cross.
It is hard to envisage anything but success for him at London Stadium.
|Mins played||2181||Goals and assists||24|
|Shots, incl blocks||53||Mins/goal involvement||90.9|
|Shot conversion, inc blocks||28.3%||Chances created/90||1.6|
Pellegrini now has an interesting tactical conundrum.
Haller performed at his best alongside a strike partner, Luka Jovic, last season.
While the Frenchman has the tools to lead the line on his own in a 4-2-3-1 formation, Pellegrini must be pondering a switch to 4-4-2 to make best use of his latest signing.
The manager used 4-4-2 on 10 occasions in 2018/19. So it would be no surprise if that becomes a more permanent shape.
With his class, the Frenchman is a player West Ham can build their team around.
Part 2: Rodri a strong successor to Fernandinho
Part 3: Willing runner Wesley ready for the top flight
Part 4: James to change pace of Man Utd play
Part 5: Joelinton can be Newcastle's very own Firmino
Part 6: Ndombele can help Spurs move into higher gear
Part 7: Pepe play will bring wow factor to Arsenal
Part 8: Kean will give Everton new dimension