The DRS problem: it's not the humans
The DRS is a system in which umpiring decisions can be reviewed by players. Events on the field can also be reviewed by umpires in some circumstances before a decision is made. A widely held view about recent problems with the system is that while the DRS is fine, the way it is used by players, and on occasion by umpires, has caused difficulties.
I hold the view that the problem, if there is one, is with the system, not with the way it is used. The way the system is defined strictly determines the way it is used.
The DRS system I refer to is described in detail by the ICC in its Playing Handbook (pdf). It is worth clearing up a few misconceptions at the outset.
The TV umpire does not overturn a decision under the DRS. The TV umpire is explicitly prohibited from discussing whether or not a particular appeal should result in an out or a not out. Further, there is no standard in the DRS requiring "conclusive evidence to the contrary" to overturn a decision, as many commentators are fond of telling us.
The rules make only three points. First, the TV umpire must limit himself to the facts. Second, if some of the evidence requested by the umpire on the field does not permit a conclusion with "a high degree of confidence", the TV umpire should convey to the umpire on the field that a conclusive answer is not possible (the conclusion in this case is not the decision itself but about individual points of fact potentially influencing it). Finally, if some information is not available to the TV umpire, he is required to report this to the on-field umpire. He is also required to provide all other evidence requested by the on-field umpire. If we go by the ICC's DRS rules, at no point in the review process is the TV umpire required to provide a definitive conclusion by putting together all the evidence.
The Guardian reported that the ICC did admit to a protocol error in the way the umpires addressed Australia's review in Jonathan Trott's first-ball lbw dismissal in the second innings at Trent Bridge. The ICC has declined to say what the protocol error was, citing a long-standing policy of not revealing communication between umpires. A number of observers think that the absence of one Hot Spot camera angle should have automatically meant that the outcome of the review should have been inconclusive, allowing Dar's original not-out decision to stand. I think this is a misreading of the ICC's DRS rules.
Let's reconstruct the case of Trott. Umpire Erasmus in the TV umpire's box would not be asked "Is Trott LBW?", or even "Did Trott hit the ball with the bat?" Going by the ICC's rules, he would be asked a different series of questions. Does Hot Spot show a touch? No. Does the replay show a touch? Inconclusive. No clear evidence of a deviation. (Some people have argued that there was evidence of deviation on the replay. I disagree. As did Michael Atherton on live commentary.) Does the square-of-the-wicket Hot Spot show a touch? This angle is unavailable. Can you hear any relevant sound on the stump microphone? Inconclusive. Did the ball pitch in line? Yes. Did it hit the pads in line? Yes. Does the ball-track predict that it would have hit the stumps? Yes.
According to the rules, Erasmus would be prevented from providing probabilities or maybes. It would have to be yes, no, or can't say. After getting all these factual responses from Erasmus, Dar would have to make up his mind. Did what he heard from Erasmus merit reversal? As we know, he decided that it did. The protocol error could have been that Erasmus neglected to mention that one of the Hot Spot angles was unavailable. It could also have been that Dar weighed all the facts Erasmus provided to him incorrectly and reached the wrong conclusion, though it is difficult to construe this last possibility as a protocol error, since the protocol explicitly requires the on-field umpire to exercise judgement, which is what Dar did. "The on-field umpire must then make his decision based on those factual questions that were answered by the third umpire, any other factual information offered by the third umpire and his recollection and opinion of the original incident" (See 3.3[k] of Appendix 2 of the Standard Test Match Playing Conditions, ICC Playing Handbook 2012-13).
This is the central faultline in the understanding of the DRS. To some technophiles, it promises an end to interpretation; that, with the DRS, there is to be no more "in the opinion of the umpire". Technology will show everything clearly - make every decision self-evident.
Not so. Under the DRS, a judgement has to be made about whether or not evidence is conclusive. A judgement also has to be made about whether all the evidence (often conflicting, due to the limitations of the technologies involved), taken together, merits a reversal. There have been instances where outside edges have been ruled to have occurred, though there was no heat signature on the bat.
The ICC has consistently insisted that the idea is not to render umpires obsolete. It is right, but in a convoluted way. What the DRS does is allow umpires a limited, strictly defined second look at an event. But it does so on the players' terms. Umpires are currently not allowed to review a decision after it has been made on the field. The "umpire review" element of the DRS takes place before the decision is made on the field in the first instance. Simon Taufel, who has wide experience of both DRS and non-DRS international matches, has questioned whether this is reasonable.
So far, the DRS has been badly burnt in the ongoing Ashes, and has received criticism from some unexpected quarters. Add to this a recent report that a few boards other than India's also oppose it. I suspect that the DRS will not survive in its present form for long.
The ICC is experimenting with real-time replays, which it says will allow TV umpires to initiate reviews. The ICC has long claimed that this is currently not done because it will waste time. The ICC's statistics suggest that in an average DRS Test match, 49 umpiring decisions are made (a decision is said to be made when an appeal from the fielding side is answered). Let's say an average Test lasts 12 sessions. This suggests that on average about four appeals are made per session of Test cricket when the DRS is employed. These numbers don't suggest that allowing umpires to initiate reviews will result in too much extra wasted time, do they? It should be kept in mind, though, that the ICC assesses time wasted relative to the progress of the game, and not simply as a measure in seconds or minutes.
The most damaging consequence of the DRS is off the field. It has now become a point of debate among professional observers of cricket about whether dismissals are determined by the umpire. The idea that the umpire is an expert whose role it is to exercise judgement, and whose judgement is to be respected, is now only superficially true. Time and again, eminently reasonable lbw decisions are reversed for fractions, and as a result are considered clear mistakes. Cricket has lost the ability to appreciate the close decision, the marginal event. It has lost the essential sporting capacity to concede that an event on the field is so close that perhaps a decision in favour of the opposition is reasonable.