TBF, Lenglet has played regularly at the top Spanish team and in the Champions League, so it isn't like we were getting an unknown person from Sarkovia. However his first League* games was with Torres injured. So I expect having to get used to the Prem pace and how we play suddenly in the last 9 games hasn't been the best intro. Same with Torres not looking like a good "strong" defender after being thrown in when Mings was injured.
*I'm aware he played for Spurs last season, but that was 7 months gap in league games and different styles.