Not that he was given too rough a ride by the people who, in the final analysis, have been paying his salary these past five years. True, Liddiment, nicknamed Disco Dave by some industry wags because of his enthusiasm for 70s dance music, caused his own Saturday Night Fever (sorry) when he scheduled Premier League football highlights into the crucial early peak slot traditionally owned by Cilla.
And, yes, he took a lot of flak for that ratings failure - but some advertisers actually admired the bravery of the Saturday strategy and argued that if he'd been allowed to stick with it, it might have come good.
In critical terms, he notched up some pretty decent achievements on the credit side - acclaimed dramas such as Cold Feet and Bob and Rose; but ratings performance overall has been soft, especially in comparison with an ebullient BBC. So what should we feel about his imminent departure? And what sort of challenge will Liddiment's successor face? Is there scope for improvement in ITV's ratings performance? Is it a poisoned chalice - a nightmare job, an accident waiting to happen?
Cynics would argue that all you need to do at ITV is commission a handful of gut-wrenching, tender-yet-gritty dramas charting the lives and loves of emergency police vets in the Peak District (or possibly the Yorkshire Dales) during the 50s. Then a vehicle (other than a bathchair) for David Jason. A bit of Robson Green and Ross Kemp. The trashy soap operas and gameshows look after themselves. Sorted.
Andrew Constable, the head of media at the brewer Coors, believes that Liddiment has been doing a pretty decent job. "We all make mistakes but few have their reviews made quite so public, he argues. "If you take away some of the things he's been most heavily criticised for - such as the football - he's done well, especially given the funding he's had.
I think the whole episode actually highlights the strength of BBC funding.
The BBC seems to have more money than it knows what to do with and that's especially relevant when the economy is the way it is currently. I think his decision to go is related to that. I have a fundamental problem with such a well-funded, supposedly public service, broadcaster that seemingly isn't controlled by anybody."
But is Constable optimistic that the incoming director of programming will make a positive impact on ratings? It's not that simple, he reckons.
"A lot of the decisions that will impact over the coming months have already been made by David - and if ratings improve, he should take the credit. The impact made by the new man or woman won't be felt for probably 18 months."
Others are slightly less generous in their assessment of Liddiment's tenure - and are more insistent that an improvement can, and should, come quickly. Marc Bignell, the head of television at OMD, admits he hasn't been much of a Liddiment fan. "I think he became quite isolated in his approach to programming and scheduling, he states. "For instance we did some research about the proposed 7pm slotting of The Premiership which showed that it would fail. We also did research into the rescheduling of daytime following the loss of Richard and Judy and Home and Away. That research was completely ignored. I don't think he ever listened to anyone outside his own circle."
Some observers point out that many of Liddiment's ideas were actually pinched from other markets. And yet even here he still managed to turn gold into lead - for instance with Survivor, a huge hit in other countries that underperformed spectacularly on ITV. And many critics held their heads in dismay when, having lost Home and Away to Channel 5, Liddiment brought back Crossroads, a limp time-warp of a programme that sent out all the wrong messages about ITV's ambitions.
"ITV may not be at rock bottom but it's not far off - so it can be improved. I think there are many things that it will be fairly easy to put right. And, yes, the BBC is aggressively commercial but that's not new and it has weaknesses that can be attacked, Bignell states.
Some observers were encouraged by the autumn schedule unveiled a couple of weeks back. Chris Boothby the negotiations director of BBJ Media Services, comments: "It is vitally important that ITV can maintain momentum on the back of that. It finally suggested that ITV is confronting its problems and is prepared to do something about them."
He adds: "While ITV has haemorrhaged audiences over the past few months it should be noted that Liddiment did have some notable successes in a difficult environment and did show some capacity to experiment and innovate in scheduling. But too often his hands were tied by petty in-house squabbling and the massive drain in resources that ITV Digital became."
And whatever happens, Mick Desmond, the joint managing director of ITV Network, states, the good news is that the transition period will be smoothly handled - Liddiment is staying on until a successor is in place. "The way David is leaving is very professional and open on both sides and we will be able to make a very considered change, he points out. "David has already spent a lot of time working on what will be needed for the back half of 2002 and for 2003, so it will all be in good order for a successor. There will also be substantially better resources available. We've had problems - we recognise that and we intend to put them behind us. And it's true that we have faced a resurgent BBC but we are not bleating about that - we have to get on with our own game."
So, what type of person should Liddiment's successor be? Someone from within the ITV family, someone who knows how to survive the internal politics?
Or would it be better to get a fresh perspective by poaching talent from a rival broadcaster? Desmond responds: "The key determination is that we want someone who is up for the fight. People are already saying that the autumn schedule looks a lot stronger and I think that's proof that we are up for the fight back. We're looking for someone to help lead that. There are a lot of names coming forward. David used to say that he had the best job in television and I think he's right. I don't think you should underestimate the value of that."