A number of venture capitalists have been linked to speculative takeover bids for ITV after a Carlton and Granada merger, which Eyre believes would be "disastrous" for the network.
Elstein's plans include spinning off the sales houses, slashing jobs and reducing the number of in-house commissions, as well as replacing the management team.
In a report in The Observer, Eyre said the idea of venture capitalists backing a takeover of ITV would be severely detrimental because venture capitalists would "want a short-term return, which would eat into investment".
Eyre said that Elstein was the "wrong guy and it's the wrong plan for ITV".
Reports have linked Richard Brooke and Damien Harte, former finance directors of BSkyB and Five respectively, to Elstein's proposals, as well as Malcolm Wall, chief operating officer of United Business Media, and Five's deputy CEO Nick Milligan.
Venture capitalists West LB and Media Ventures Investments have also been linked to possible takeover bids, according to reports earlier in the year.
Eyre believes that the merger of Carlton and Granada is crucial if it is to compete effectively with the BBC and BSkyB.
"I think it's exceptionally important that ITV does play a part of a Big Three," he said.
His comments echo those of BBC director general Greg Dyke, who last week urged the government to drop ITV's £300m broadcast licence fees to enable it to be one of what he called the three "gorillas" of the UK broadcast media.
The Carlton-Granada merger is currently in the hands of the Department of Trade and Industry following a lengthy inquiry by the Competition Commission aimed at preventing a combined ITV pushing up the price of air time, or at least appeasing opponents of the deal.
The commission has suggested two possible solutions. The first proposal would see a minimum amount of ITV's airtime auctioned off each year to a third party, which would then be sold to a secondary market.
The second would allow advertisers to renew share deals, but based on the same terms as previously agreed. Advertisers would also be allowed to reduce the number of ads shown if ITV's share of viewers decreased, without losing their discounts. Share deals give advertisers discounts over a period of time if they agree to spend a certain amount of money.
The Competition Commission filed its report to the Department of Trade and Industry on August 21, just ahead of the due date of August 26. The DTI has around 20 days to consider the investigations and the final decision is expected in the next two weeks.
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