Álvarez is used to playing vs teams that defend with a low block. River is the City of Argentina. Everybody parks the bus vs us, even boca.
Gallardo and Guardiola share a lot of the same premises in terms of tactics: suffocating high press and a lot of ball possession. Gallardo might be a bit more direct than Pep, but in general terms they are very similar. Even on the scheme: 4-3-3 with a false 9 and fullbacks that get inside to work as defacto midfielders.
When Julian was rumored to go to United I was worried because they are a machine of stunting players' developments, and I always thought you guys were the best fit for him instead.
No hiring is a guarantee of success (if not, just look at Grealish) but I think this one is as good a get as you guys could have had, outside of getting the Halands and Mbappes of this world. The best player in South America, who happens to fit your style of play as a glove, and extremely cheap for your standards.