Successful 2nd spells at clubs

Claudio feckin’ Pizarro at Bayern and Bremen.
 
Jonny Evans at United.

Was Rooney at Everton successful? Felt like he did well there even if in his 30s and scored that goal from halfway line (just checked - that was vs West Ham, he scored similar goal for us in 2014 against same team).
 
Martin Keown had two spells at Arsenal - left after breaking through in the 80s to develop at other clubs and came back in the 90s to take his place in that famous defence.
 
Although he wasn't as important as he was in the 11/12 season, Diego Ribas played his part in helping Atletico win the league in 13/14 when he returned in January. He also helped them get to the CL final with that incredible goal against Barcelona in the semi final.

I will always think it was a shame he played no part in the final itself.
 
Probably Nils Liedholm at Roma. First stint wasn't particularly eventful, with an average Serie A positioning of 7th and no trophies. Second was spectacular, though — first Serie A title in more than 40 years (ahead of a Juventus team that was managed by Trapattoni and boasted the talents of legends like Platini, Zoff, Scirea, Boniek, Cabrini, Tardelli), reached the European Cup final in 1984 (another first for the club), won 3 Coppa Italia.
Carlo Ancelotti: “I had some important teachers and on a human resources level, none better than Nils Liedholm. In the 1980s he was fundamental, as he didn’t put pressure on.”
Football Italia: Ancelotti, Sacchi & Pep on mentors.

Others, like Nereo Rocco (Milan) and Marcelo Lippi (Juventus) did quite well in their second stints at those clubs, but neither evidenced the same sort of improvement and upward mobility.

As regards players, maybe Jupp Heynckes at Borussia Mönchengladbach? First stint was decent, with 27 Bundesliga goals in total, not bad. Then he joined Hannover 96 and stayed there for 3 seasons. The second stint was extraordinary (as he ushered in a golden period for the club with Weisweiler, Netzer, Vogts, Wimmer and the likes). 232 goals in total (including 195 Bundesliga goals, the most by any player at the time for one club, trailing only Gerd Müller with Bayern Munich), a 3 year stretch where he scored 129 goals in all competitions, European Cup top scorer, twice Bundesliga top scorer, twice UEFA Cup top scorer, Cup Winners' Cup top scorer, 4 Bundesliga titles (as many as Franz Beckenbauer, for reference; those Mönchengladbach teams were a force to be rockoned with on the domestic front), reached the final of the European Cup in 1977.

Again, very few, if any, evidenced the same sort of improvement and upward mobility.
 
Klinsmann brief 2nd spell at spurs was a huge success, they looked like they were going down but for his goals.
 
Mourinho's second spell at chelsea went well enough. He won them a league title, even if it ended in meltdown the season after, you would have to say it was more a success than not.
 
John Wark at Ipswich. Had three different stints with them in between moving to Liverpool and Middlesborough. Made over 500 appearances in over a 20 year career.

Shinji Kagawa. Can't forget Free Shinji! Had a relatively decent return to Dortmund. Scored some absolute worldies for them on his return.
 
Pogba's second spells at United and Juventus?

I remember reading at the time Mo Johnston signed again with Celtic in the early summer of 1989, how did that work out?
 
Don't think Carvajal and Casemiro (technically at least) at Real were mentioned.
 
Matic's second time at Chelsea, he won the league twice and played an important role.
 
Antoine Griezmann with Atlético Madrid must be up there, at least looking at the recent examples.

Regarding Trainers, Carlo Ancelotti with Real Madrid.
 
Darren Ferguson in his first, second, third and fourth spell at Peterborough?
 
Isn’t Di Maria doing well at Benfica this season?
Yep, genuinely think he's one of the most underrated players of this generation.

Tevez is the best one, he went back to Boca, left for China and Maradona gave that quote about him filling Santa's sack with money :lol: and then came back again.
 
Spurs have had a fair few of these all at the same time!

Crouch, Defoe and Keane all left then came back and were pretty successful.