Everything depends on what player he takes the spot from. A random nationality that does not play in any NT and he is sure to increase your merchandise.
If a foreign player replaces a domestic player - regardless how bad this guy even might be - you won't see an increase. Even if you replace a foreigner with a better foreigner, your merchandise will go down, as the share of domestic salaries declines.
Größter Knecht aller Zeiten aka His Excellency aka President for Life aka Field Marshal Al Hadji aka Lord of All the Beasts of the Earth and Fishes of the Seas aka aka Conqueror of the Buzzerbeater Empire in Europe in General and Austria in Particular