He does have great technical ability. But he lacks the athleticism to make it at the highest level. That's why for his sake he needs to move on to somewhere like Palace or West Ham, or abroad to a less physically demanding league.
He's 22 now, not a kid. Doue at 19 is already a better player for example.
Also - what position does he play? He can't be a winger because he isnt quick enough. So really he has to be a 10, and you have to be exceptional to play as a 10 at a club like Liverpool. He's good, but he's not exceptional.
If he wants to stay, he'll have to accept being a sub - he is much more effective coming on the last 30 mins when we need a goal and the opposition are tiring and sitting back, or the game has opened up and he has more space to work in