Numerous former players have said they were promised new contracts if they achieved promotion, survived, did well etc and the club hierachy at the time didn't follow through and they ended up falling out and leaving. Off the top of my head Ellington, Roberts and Chimbonda. I also remember us not engaging in contract negotiations with key players until their deal was due to expire in a matter of weeks (Diame, Scharner, Rodellega, DiSanto, etc) we know it likely wasn't just those players privately rejecting deals as all contract renewals only happened at the end of the season. I also remember Moses and Heskey publicly stating they wanted to stay and sign new deals before they headed into the final year but neither happened so when offers came in from bigger clubs we were not in a strong position to hold out for a bigger fee due to them being in their final year.
We probably cost ourselves millions by trying to put off renewals to save thousands back in the 2010s. But thankfully we've not been like that for a good while.
We've got completely different recollection of events then on numerous players:
Ellington - said when he left that the contract he got offered at Latics was actually worth more than the one he signed at WBA. Latics one was loaded with bonuses based on goals, appearances & finishing league positions etc.. whilst the WBA one was a bigger basic, guaranteed salary. With latics tipped by many to head straight back down it made perfect sense not to guarantee any player a large basic salary if the Prem money was only going to last 1 season. Judging on how he performed after leaving I'd say Latics did the right thing. It's only very recently on twitter that he's hinted he'd been promised something or a couple of years that they hadn't delivered on which made him want to leave
Chimbonda - from what I remember at the time he said that his agent told him loads of clubs wanted him & were offering him big money & as he wasn't going to see anyone for 5-6 weeks, he thought he needed to hand a transfer request in straight after the game so he didn't miss out on these. I've never heard or read him saying he only wanted to leave coz he was promised a better Latics deal & it was never delivered
Roberts - I do think went to the club at the end of that 1st top flight season to negotiate a new deal & Whelan said no coz you only signed that one 12 months ago. Baffled me at the time even though I get the rationale behind hit but I've no doubt that his replacement (Heskey) probably cost the club far more so I'm not sure I'd describe it as penny pinching
Heskey - I remember him saying in that season he left half way through that he would not be signing a new deal at Latics regardless of what was put on the table. Lets not forget he'd got back in to the England set up & was being lavished with praise after years of getting stick & he wanted to move back up the ladder it was nothing to do with not being offered a new deal earlier
Moses - never said anything of the sort about wanting to stay if he'd been offered a deal before the final year of his contract. He never even made it to the final year of his contract. In April 2012 (when he still had about 15 months left on his deal) his agent announced that he'd pulled out of contract talks that were due to start with Latics because he wanted to leave that summer
Diame - was offered a deal during the season but said he wanted to go coz he hadn't played as much as he'd liked & only ever saw Latics as a stepping stone
Scharner - again was offered deals but turned them down coz he wanted to play in midfield
Rodallega - was offered new deals but turned them down as he wanted to move to a "bigger" club. It was known well before the season ended that he was going.
Di Santo - his agent was dropping stories from as early as October 2012 that he was ready to turn down his contract offer from Latics coz he knew he'd earn more as a free agent in the summer
Lets not also forget that in the era of these players Latics were more often than not fighting relegation so players were reluctant to accept offers from us when they thought that we may not be playing top flight football the following season.
Latics did not & have never, left negotiating new contracts with players to within weeks of them due to expire - they may still be negotiating with them at that time but that isn't always the fault of the club