First example, yes its not great value. But say for instance he is the last 4th round graded player left on your board and you get him, then that value might be "good enough". And its easy to take this too far. You could keep trading down and make value picks consecutively at the end of whatever round is loaded on your board, but you have reduced the chances of you getting a top tier talent in the early rounds.
Value in terms of just the draft (not the longer term payoff as Rand discusses in answer to you) is more about the pick and what it represents than the player itself. Did you use your 3rd round pick in a panic on the last safety and take a talent you rated for the fourth round? Do that a lot and you literally reduce the talent on your team over time. You could trade down and get a second fourth or fifth round talent.
Second example is good value but also collect additional risk.