The Polish defensive midfielder was on the fringes in Paris and moved to England in search of game time ahead of the World Cup.
Given the wealth of attacking talent they've recently signed, and the fact defensive midfielder Thiago Motta is now 35, PSG may well have a place for him next season. But for now he is West Brom's.
The Premier League boasts a number of solid, physical midfielders who do a similar job to Krychowiak and it's often considered a league which new signings from the continent will take time to adapt to.
So we took a look at the 27-year-old's stats alongside some of the league's best in a number of categories.
As those who watched him at Sevilla may have expected, he comes out of this test as a good all-rounder. They might be surprised to see his pass success slightly lower, but that is almost certainly down to the direct style of play under Tony Pulis.
At his previous clubs he's been just as effective at building the play for his own side as he has stopping the opposition, and he does have one assist to his name this season.
His defensive contribution is considerable, though, standing up to his competition in every category, and he leads the league when it comes to interceptions per 90 minutes. He also gives away relatively few fouls for a player in his position.
Oriol Romeu of Southampton regularly features among the top defensive midfielders, statistically, while Wilfred Ndidi has the task of replacing some of what N'Golo Kanté brought to Leicester and puts up some good numbers, at least on the defensive side.
It was something of a surprise when Krychowiak rocked up at The Hawthorns. His pedigree, after all, suggests he could play at a far more glamorous club. But the Baggies moved quickly to bag the Polish schemer and he is quickly turning into one of the signings of the summer.