in 2019, the New York Giants traded for Leonard Williams halfway through the season. In order to keep him around for more than just a half season and retain some value from their trade, the organization has placed a franchise tag on him for at least this season. They can still work out a long-term deal by July 15th, but his contract negotiations could be the least contentious thing the Giants will have to have to speak with him about.
The Giants want to tag him as a defensive tackle, which is a much less expensive position. Williams believes he's a defensive end. This kind of dispute could easily spiral into a grievance because Williams could miss out on money he thinks he's owed.
Pro Football Reference recorded him as a defensive end in every season he's played, and when Williams was drafted, it was as a defensive end. By marking him as an ambiguous 'defensive lineman', the Giants have avoided specificity and can claim he's a tackle.
It also remains to be seen how he'll be used in the upcoming season. They could very well play Williams on the interior, as he spent a significant amount of time there in 2019.
Whether the Giants truly believe he's a tackle or they're simply pulling a shady move to save some cash, Williams is missing out on over $1.6 million, and he's going to want to make up for that, either by filing a grievance or securing a great deal.