If you're saying he might do well at Manchester United then that's totally fine but don't say Jackson did well at Chelsea because you clearly didn't know Jackson. Jackson was supposed to perform at Chelsea after his move from Villarreal but he failed to improve despite been giving several chances. Do you know that Jackson has been at Chelsea for 2 seasons? Do you know that in these two seasons his been their striker and has managed just 24 goals as a striker in 2 consecutive seasons. Scoring 14 goals in his first season in EPL and 10 league goals in the just concluded season and 10 assists in those two seasons combined. That's 24 goals in 65 appearances. Does this statistics look like a statistics of a player that performed? Like I said earlier, you clearly didn't know or watch Jackson play at Chelsea.
Chelsea created lots of chances for Jackson, which he should have converted. Chelsea and Manchester United suffered the same problem with strikers only that Chelsea combined are more preferable, at least we can count moment when Jackson was able to contribute to Chelsea victory, Manchester United had the worst set of strikers which landed them 15th position last season.
If Maresca don't act, Jackson shouldn't start any Premier League match ahead of the new signing, we can see the difference between Pedro and Jackson, there is nothing else to see again from Jackson, he had the opportunity but couldn't perform.
Chelsea and Manchester United are in a very poor state at the moment, Manchester United was even worse last season. Those who bet on them lost the most, Manchester United played the best role in losing money to gamblers. Although they have made some improvements this season, Manchester United and Chelsea still have weaknesses in the attack department.
These weaknesses must be overcome and the best time has come for Jackson. But Jackson could not take advantage of this opportunity, he is a promising player but his performance has been questioned, which is why Jackson's own failure has been revealed due to his poor performance.