Problems are your facts are wrong.
Do your homework and try again.
Alright.
Pogba: Joined Le Havre from Torcy in July 2007. Left for Man United in July 2009. Total time: 2 years.
Kane: Joined Arsenal in 2001, left in 2002. Total Time: 1 year.
Mahrez: Joined Le Havre from Quimper, where he made 27 appearances with their senior team, scoring a goal.
E. Mendy: Joined Le Havre at the age of 13, in 2005. He stayed there one season before leaving to join a lower level team, CS Municipaux Le Havre, where he stayed for 5 seasons, before joining Cherbourg. Total time: 1 year.
F. Mendy: I will correct myself, I meant he spent two years in Le Havre's youth academy before graduating, a la Bellerin at Arsenal. Joined the youth academy in 2013 and graduated in 2015. He spent the vast majority of his youth career at PSG, a la Bellerin at Barcelona.
Anything else you need me to do for you?
Like I said, happy to discuss. Pogba to Gnabry are similar levels, at least over the last couple years. Mahrez joined as a young senior player, so let's compare to Fabregas or RvP. E. Mendy was there one year before dropping to a lower level. Just like Kane. I'll take Kane. F. Mendy compares to Bellerin or Szczesny. Then it's B. Mendy and Payet vs Saka, ESR, Nketiah, Nelson, AMN, Willock, Iwobi, etc.