Case evaluation is a difficult skill to learn as an attorney. There are no crystal balls. As Yogi Berra famously said, "it's tough to make predictions, especially about the future."
A patent prosecution attorney is constantly required to analyze an invention against only a partial view of the state of the art and with no idea where and when infringing products will enter the picture, and with what design arounds and further improvements.
What makes such evaluations doubly difficult is that many cases are finally decided on issues that are often tangential to the main dispute. For example, reviewing PTAB decisions in light of the full history of a case often reveals that the controlling facts and issues have little to do with the real invention or aspects of the case that seemed most determinative at the beginning.
This phenomena is much like a sports match where a fan has a prediction in their mind as to how the match will go given the statistics and other pre-determined information available at the start. But what makes watching such competitive matches exciting is that many times those initial predictors completely overlook how one player may capitalize on mistakes by the opponent, or how external factors can interject unexpected twists and turns.
That is why some players (or attorneys) seem to be able to find success in matches (or cases) that look unwinnable from an objective view at the beginning. One must always know the weaknesses of their case, but being able to adapt to changing facts or circumstances, including missteps by the opposing side, is often more important than thinking you have a winning case from the beginning. Just like in tennis, sometimes it is more important to return the ball with strategic placement than go for the winning shot.
In patent prosecution, the Office often falls into the trap of shooting its own foot due to its heavy bureaucracy and myopic viewpoint. That is why it can be helpful to make sure and force the Office to be explicit in its reasoning and analysis. When pressed, the Office can often over-reach in its position and open up holes that make an affirmance by the Board extremely difficult. In other words, when the Board can find a reasonably way to explain away some ambiguous reasoning, it will do so for an affirmance. But, when there is just no reasonable rational basis for affirmance, the Board will often simply reverse rather than try to restructure a proper new ground of rejection.
In a recent appeal case, the Office's original rejection (while improper) was somewhat ambiguous but not completely unreasonable on its face. However, when pressed (via a petition aimed at confirming whether new reasoning in the Examiner's Answer represented a new ground of rejection, and designed to force the Office to take a clear stance), the Office doubled down on its position and opened up a new line of attack by relying on completely unreasonable logic. In another appeal case, when the Office's lack of citation to authority was questioned, the Office doubled down on the idea that it did not need to follow any such authority... sometimes Christmas comes early.
So, in tough situations, do not give up hope. Look for opportunities to capitalize on the arrogance or over-confidence of an opponent that is not taking proper account of the way in which a match is progressing.