From August to December, Wijnaldum was solid and finding his way in a new team/club/role. It's telling that we were in incredible form then.
From the end of December, Lallana's productivity has fallen off a cliff and Wijnaldum stepped up massively.
First half of the season he was part of a well-oiled machine, second half he's grabbed the steering wheel. Him and Mane have paid back their transfer fees handsomely, in my view.